It's too hard to get into the bigger ones right now, but you can always invest in the smaller ones.

My current business is funded in pure BTC from outside investors. That's not an invitation / solicitation, and I am not taking any investments at this time, but is just to make the point.

If you want to invest in BTC businesses, you certainly can. Just go find some that you believe in, and make sure you do it all legally, to protect yourself from the feds and from scammers.