Financing the race team operating budget is traditionally an ownership function, not a driver function, duh. And what is or isn't a "gravy train" is a matter of perspective and point of view. I believe racers are almost universally underpaid, although the few at the very tip of the iceberg are doing fine. Compared to other sports, Nascar drivers are significantly underpaid relative to several major stick-and-ball leagues... primarily NBA, MLB, the major soccer leagues, and maybe NFL. There are many reasons for this... business models, organizational structures, popularity of the sport, and others.
OTOH, comparing the many branches of the motorsports tree, Nascar has long been the most lucrative and financially vibrant branch. According to the annual Forbes analysis, last year Nascar had 13 drivers at or above the $12 million range. In contrast to this, F1 has probably three in that range, probably three in MotoGP, and zero elsewhere in racing. I'm sure Nascar will have fewer this year... Tony Stewart has retired, Carl Edwards has retired, Danica has substantial sponsorship shortfalls.
And perhaps still fewer next year, but it's still a damn good job, driving stock cars for a major Nascar team. It's likely to remain a damn good job, because the driver makes a huge difference in results in Nascar.
@Acs may not believe it, but all he has to do is compare results... JJ versus KK, the 42 versus the 1, the 18 versus 11 or 20. By contrast, F1 is two-by-two according to team. Owners will gladly pay for that, unless they absolutely cannot pay for it. That's not a bad place to be, IMO.
The only "gravy train" in Nascar is the amount of TV money flowing to the racetracks, IMO. The cozy and incestuous relationship between Nascar and ISC is the real culprit here, as
@gnomesayin pointed out.