Any kind of motorsport, even karting is very expensive. There’s no way you can even get started without having a lot of money behind you but to get to F1, the drivers have to go through so many different racing series, anyone lacking the necessary talent, regardless of how much money their parents have would be found out before they got anywhere near an F1 car.
The best young drivers will be picked up by the major teams junior programmes at a very young age. Even for those drivers, the pressure to perform is immense and they are never far from being replaced by the next up and coming talent if they aren’t getting results.
The drivers that have fended off all of the competition, from their early teens or younger, usually become the top F1 drivers.