Yes, you have a point. The "soft-books" (FanDuel, DraftKings) use the justification of being a form of entertainment as the reason to limit players. Fair enough, I have no personal issue with that.
As for who is losing money, I think you're also correct about that. Both the sportsbook and losing bettors will subsidize the "sharp bettor".
It's also worth noting that some sportsbooks (the more well established ones like Caesars and Pinnacle) do limit all players equally. That's because the do as you say and act like a marketplace to pair up both sides of the bet.
The problem with entertainment books is that they often pick a side on the bet so each side is not equally balanced. An attempt to maximize potential profits for themself instead of the traditional strategy to minimize their risk.
Echoing another comment, one huge problem with the current sports betting market is banning/limiting winners.
I started prop-odds.com to help the more mathematically inclined gamblers take advantage of mispriced odds or let them build and backtest their own models. So while it's actually not too difficult to beat the book, the challenge comes from evading their detection and getting banned.
Hey, sorry for a late reply! I've just updated our website's Features page [0]. It lists all the sportsbooks and sports we currently support, and what will be added next.
Some books we're able to partner with and they give us an API to access the data through. Other we do need to scrape, given that there is no explicit "you can't do that" in their Terms & Conditions. Some books do have such a statement, so we aren't able to offer those.
I built prop_odds [1]. It's an API offering live (and historical) sports betting odds from different sites.
I've been working on it for about 2 months. While not quite at 2k/month yet, it's nearly there and progressing in that direction. Revenue is coming from several customers who are using the data to build Discord bots that alert them (and their own paying users) about good odds, arbitrage opportunities, etc.
I use Obsidian for note taking and pretty much anything I need to write down. I like it because they're just markdown files and it's easy to back up with Git.
It also has lots of extensions too. Including vim!