On the topic of paid DMing: I personally don't see a need for this in my life, but I think it's reasonable for such a thing to exist. This individual venture capital-fed endeavor, however, seems really speculative to me and I hope that VC fund is ready for a potential total loss. Paid DMing enough to help pad the income of some massively 'gig economy' multi-job individuals who are also selling plasma and waiting tables 4 nights a week while in in grad school or something? Highly plausible. Paid DMing such that a larger company can quality-check and hand out assignments and take a cut off the top or whatnot? Possible, but not overly likely. The need for there to be something to skim off the top is going to either price a huge number of potential customers out of buying the thing, salary cap the thing down to rather cash-hungry individual (who are not inherently going to be bad DMs, but with the high variability of DM quality out there, bottlenecking of any kind is going to be risky), or just keep the total buyer-seller totality down to a very niche market.

Personally, I like to get paid when I do some work.
Right, but not every work someone is willing to do is going to lead to payment. If you've been on D&D reddit pages, there are oh so many people who would very much love to sell you drawings of your PC. I'm sure a good half of them or more have sold at least one picture. I also think the number of them who are paying their rent doing so is significantly less.
The problem is exactly that what should be "play" - that is, activity that aims to produce nothing other than enjoyment for its own, is transformed into "work", that is, activity that is supposed to create some societal value and merit recompense in return. I do not blame this on the people who do this for a living - the way society is currently structured requires us to earn money however we can to survive, and if your expertise in your hobby helps you earn a decent living, more power to you.
But the larger societal trend of commodifying everything is worrying IMO. Not everything needs to be a source of income, and more often than not turning something from play to work actually causes what made it fun to disappear. I do dislike how e-sports and professional TCG tournaments have created a class of overly negative people who no longer play for fun but chastise others when they play suboptimally, for instance. There's a reason everybody complains about LoL being extremely toxic, and I think the prominence of e-sports pushing negative or perfectionist people to the forefront is partly to blame.
It's hardly a trend. Everything has always been commodified. Some people can grow food, some people can make flint axes. The people who grow the food swap it for flint axes.
On everything being commodified: There clearly are things that do not fit into the direct-transfer-of-goods-and-services that an Econ 101 class would model things. There are plenty of devotions of time and effort that might broadly fall under the 'establishing/reinforcing community cohesion,' along with 'providing a communal social and mental wellness.' Those (in admittedly as broad a brushstrokes as I can paint) tend to be where plenty of leisure activity tends to fall -- the local fair, volunteering for the parks committee, adult softball leagues, and so on. Plenty of them have a commodified aspect --the local fair has artists and food venders, someone is selling those softball uniforms (and maybe someone in the league is paid a pittance for organizing the thing), but it is rarely the primary focus. Of course, these social cues provide communal benefit, leading to the Anthro, and Phil 101 (and Sociobiology 201, or whatever it would be) courses to have a big discussion on whether there really are truly altruistic acts.
There is no such thing as a "pre-capitalist society". Capitalism was invited the first time someone swapped an axe head for some food.
It was used for gambling. The same as dice, cards and Backgammon. Whatever the reason it was fist invented, it was popularised because people could make money with it. Just like D&D. Without monetarisation we would never have heard of chess or D&D.
That may or may not be the case. The wargames D&D came from (or even
Hnefatafl and such in earlier eras) were likely used in training would-be warriors in basic tactical thinking. Many other games, while it's possible that gambling was a primary purpose for some, it seems unlikely that it was the primary motivation for all of them. At the very least, many games have been invented alongside more gambling friendly games that would have existed at the same time (knucklebones and Go, for example). Pre-modern people aren't different from modern ones in this regard: sometimes you do things to make money, sometimes you are killing time* and sharing comradery with the people around you.
*one thing I found fascinating in my anthro courses was the realization of how hard logistics were in many times and on many endeavors. If, for example, all the farmers were to spend the time between planting and harvesting helping build the local large stone object we now know them by, some of those people ended up arriving at the build site days or weeks ahead of the main workforce, and often had huge wait times before there was anything of consequence for them to do. See also ocean travel.
D&D, when it came out, was absolutely a business venture. I don't think Gygax or anyone else was shy about that. Too true as well is that, practically by the time it hit shelves, there were other people trying to make a buck or two as well, be that through pre-made
character sheets, third party
supplements, or wholly new similar
games. That said, it was a game played amongst people who usually played for fun with other people who played for fun and, barring being a creator or FLGS-owner as well, weren't making a living off the thing. I think the community has always had a bit of push and pull over what and when and where the lines are for what is acceptable monetization and not. Probably not dissimilar to debates I've seen in those adult softball (or particularly Ultimate Disk) communities over whether organizers should receive compensation (and how much). For many people, when something changes over from a league as a nonprofit that compensates an organizer for their time and efforts (with significantly-less-than-living-wage amounts) over to a for-profit business with full-time salaried employees (especially if there are ones not out there on the field/doing the actual DMing), that's a dividing line.
Personally, I don't care overly one way or another, so long as for-profit DMing does not become dominant enough that WotC gears their products towards the market at the expense of casual hobbyist gamers/gaming. Even then, it'd just be more incentive for me and my groups to play not-D&Ds.