@bloodtide I'm just going to say that as a DM I would be
delighted if the characters in my campaign bought an inn, adopted a baby, wanted to rob a bank... Because it would mean that they were engaged in the campaign world.
I see my role as a DM not as the one providing a story, but as
facilitating a story. Ideally, the characters and players are the drivers of the story. They are choosing what they are interested in and making meaningful choices. I then place interesting obstacles in the way of their goals and let them come up with creative solutions.
In my last campaign, the characters were supposed to take down the big bad vampire queen. They did so, but along the way they also started multiple temples, pursued rumors of hidden treasures, started a revolution, made alliances with villains rather than fighting them, and overall had a lot of fun engaging in the campaign world.
You can see these actions as the players being "random," or you can see them as the players enjoying the sandbox element of D&D that has always drawn players to the game, that promise that you can try and do anything in your imagination.
I'll give you a really concrete example:
As a DM, I think a neat story element would be a big dragon coming in from the coast and razing villages. I have an adventure hook where a character's cousin arrives at the inn they're staying at, bloodied and burnt, warning them about this dragon having destroyed their hometown.
In my mind, I imagine the characters will probably ride off to save the day.
But let's say they do something "random" instead. Like one of the players suggests they buy an inn.
As a DM I'm not going to say "that's dumb" or just sit back and twiddle my thumbs until it's my turn again. I'm going to engage in the game.
Do the characters have enough money? If not, I can drop hints of treasures to be found. Maybe that coastal dragon is sitting on a fat hoard?
Once they have an inn, I'll have refugees from the coast coming to stay there. Maybe a traveling wizard knows of scrolls that could be helpful in fighting the dragon.
And then at some point I'm going to just ask the players, "Are you guys planning on solving this dragon problem?"
Maybe they'll say yes, or maybe they'll say they're not interested. What are they interested in? Maybe telling a story about a group of adventurers running an inn.
So then I'd move forward a year, say the dragon has taken over the coast and this has caused some craziness in the hospitality business. In fact, they're starting to get some real troublemakers staying at their inn. Secretly, it turns out a rival in is sending thugs to the adventurers' inn!
What will they do?
And now we have some great new adventures to play.