Born wealthy, or win the lottery. There are plenty of mediocre drivers with plenty more money than talent that still seem to show up at races all over the world every weekend.
Take that money, and spend it.....schools, media/marketing, travel. Then find another source of money, and spend all that too.
FWIW, many/most "pro" drivers have to pay for their drives, very few are "paid". I know a weekend in a decent SPEED WC-GT car can cost $20-$25K to drive, same with Grand Am Cup.