It brings greater agency in the world than "the little people". Money lets you change the world, in increasingly larger ways, in your own image. Now, you don't have to, nor do you have to want to. Most people don't have the hubris for it, never mind the money. But even without the ego, if your niece is dying from a rare blood disease, you can get her medicine that isn't being made anymore because it wasn't profitable by buying the factory and operating it at a loss.

At 10M, you have, as you say, a modest discretionary budget. Which is to say, it's modest, and not extravagant. The things you can do frivolously while spending $300k/year is different than what you can do while spending $1mm/year, but as you've discovered, unless you get disgustingly ostentatious (I hear the poors only own one car, and drive the same car for longer than a month.), taking care of your creature comforts in a reasonable way isn't that expensive. Eating $400 steak dinner every night for a year is only $150k/yr ("only"). So, other than get ostentatious (what, you don't have multiple houses in multiple states?), what do you do? Change the world.

I mean, congratulations on having joined the two comma club, your little discretionary budget is cute. At 10B, your discretionary budget is probably not actually 1000 times larger, because that's a different game of liquidity, but what you can do without remotely threatening your principal investments is way larger. At 10M, if there was a reason you had to spend $5mm, you'd have to consider it very strongly before doing it. At 10B, you can get $1mm in cash from the bank and light it on fire for the hell of it because you had nothing better to do on a Tuesday night. If there's a movie you want made, you get to ask whomever you want to star in it. You want to have a movie made about your life, starring Nick Cage as you? He's having money problems, so he'll probably say yes.

10B puts you right above Steven Rales, wikipedia article here: https://en.wikipedia.org/wiki/Steven_M._Rales. Which is to say, if you want to be a recluse, be a recluse, but 10b puts you in the club of people who have wikipedia articles written about them, despite not being a household name or noteable. Edward Snowden has a wikipedia article, and he's not a billionaire, but he was forced to do some world changey shit to get that. You'd get that simply for having that kind of money. Poke around the Forbes billionaire list - https://www.forbes.com/real-time-billionaires/. See how many names you recognize as household names. 10b automatically dumps you in those leagues. Marc Benioff's #240 with an estimated $10b. Now, you may not want to be, but if you're familiar with his work, you can do anything like that, on that level. Own a local sports team. It's a bit different rooting for the local sports team when it's your sports team.

Personally, I'd fund science and research and the arts rather than have anything to do with sports. Affordable healthcare. Buy buildings and give buildings to Planned Parenthood so they don't have to keep moving around (something about protestors makes their neighbors nervous). Fix homelessness (which is a big problem, but I'm sure $10m/yr would help lots of aspects of it). Start a chain of coffee shops and over-employ people so that the people that work there have regular weekly schedules and can go to college.

I hate to say it, but that's really a lack of imagination. Instead of $10M principle with a modest discretionary budget, think of the unreasonable shit you could do with $10m every year. Some of it could even be good for other people.