That is why crypto casinos bankroll investments were so good for common investors like us. You could benefit from the profit made by casinos, while investing any amounts of money without any difficult or bureaucracy. Just by signing up on crypto casinos you had access to this feature already.
However, now casinos are self-sustainable and don't want borrowed funds from investors anymore.
AFAIK Bustadice and Bitvest are two reputable casinos in this forum that still offer bankroll investment, so if you really want to invest you can choose those casinos. Although it sound investing in casinos are very profitable since the house always win, but they have a rules about withdraw fees where you want to withdraw your money from the bankroll investment. It depends on each casinos, just like Bustadice who ask 2% of the total investment.
If you didn't hold for long and withdraw your investment before it reach at least 2% profit, you'll loss.
Oh, yes, thanks for mentioning these ones, although I haven't heard positive feedbacks from the profitability point of view about these casinos. If I remember correctly someone who invested in Bitvest had his investment pretty negative (in LTC currency I think), while Bustadice didn't show expressive results too. To make this kind of investment worth I believe the casino has to be very active and popular, otherwise it will be a risky deal, since few gamblers can come in, win a big prize, go away and there won't be many customers/gamblers to cover the loss the casino and investors had. Then you might have your money stuck there for a long time just to recover the same amount your deposited initially.
And as you said, there is also this cashout fee rule which discourages the investment a little more...