If your capital is much bigger than the house's value, then you are better off building your own casino, right? I see it like lottery, buying all the tickets would get you the prize but for much lower than all you spent to get it.
Granted there have been groups who have been beating blackjack before but that required a well-coordinated team, devices for card-counting, etc. It's not something an individual can do by himself.
I agree with your argument, it makes sense to buy a casino than playing with casino bankroll equivalent. Even the roulette cheating systems with magnet, lasers can be detected by casino administration with surveillance cameras. Beating the house edge is no possible for long run only hit and run strategy work for a short time period. House always wins.
With the group I mentioned, indeed they were doing mostly hit and run. Even with that though, security did managed to catch up with them. There is actually some sort of private agency that identifies these "cheaters" and the list is shared among casinos. Get on the list and you will not be allowed entry into most (if not all) casinos in Vegas.
You get on the list even for just suspected "card counting".