So, let me start by acknowledging the obvious- the thread is obvious flamebait.
Let me also state that I am a big believer that any playstyle is a valid one. What I find fun, is not what someone else finds fun, and vice versa. D&D is a big tent that allows for a variety of playing styles, and the only two things we should all agree on is that playing styles are a matter of choices, and that paladins suck.
That said, I don't agree with this comment. It's like the old saw about a poker game- if you walk into a poke game, and you don't know who the mark is, you're the mark. It's kind of the same with D&D.
If you're playing at a table that doesn't want, or like, optimization ("powergaming"), then there is no good way to to be a powergamer. No matter how much you might think you're the "good" powergamer, it just doesn't work.
Even assuming you're trying you're best, you will eventually run into the Angel Summoner / BMX Bandit problem (if you're not familiar with it, search for it on youtube ... trust me, it's worth it). Now, 5e isn't as prone to the problem as some editions (3e), but it still exists. And the generous "sharing the spotlight" eventually just becomes, "Well, gee, that's nice that you're letting us pop our wheelies, but I guess you should just summon your angelic hordes and get this over with already."
All of this is to say that the table should communicate their preferences clearly. If the table is a beer & pizza & catching up with friends table, then you shouldn't powergame. If, on the other hand, the players at your table are really into the rules and optimization, then everything is gravy. Adjust your playstyle depending on the table.
In the end, I find that players who try to optimize the group fun over their own fun, tend to have more fun themselves. A rising tide and all that.
Going back to the OP, we don't have powergamers at my main table. It's been my experience (which is anecdotal), that the powergamers who are problems tend to believe that their way to play is the "correct" way, and that powergaming is just a manifestation of a jerk-y personality. On the other hand, there are those who powergame (optimize) because they enjoy it, and once they understand that this table doesn't play that way, they have no difficulty dialing it down and fitting in - because they want to have fun more than they want to powergame.
So, wrapping up- there are all sorts of jerks, unfortunately. Some are powergamers. Not all powergamers are jerks. Optimizing is totally fine, but make sure that's what the table wants to do. In the end, like all things, communication with the table is what matters. D&D is a fun, social game, and everyone's fun is enhanced when we are pushing for the same common goal. Which is fun. And no paladins.
Some people are better at creating effective builds than others, some people are simply better at tactics than others. Give two people exactly the same builds (especially spell casters with a lot of options) and in many cases one person will be far more effective at their role than another.
But I don't see why someone who is more effective at their role automatically makes them someone that would not be fun to play with. As far as the Angel Summoner / BMX Bandit problem, the only time I've seen that is when you have some characters heavily reliant on daily/recharge powers in games that only do 2-4 encounters between long rests. That's on the DM, not the players. In my experience 5E works better in that respect than previous editions if you follow the guidelines.