It definitely varies per person.
There's clearly a level of financial uncertainty where a founder is LESS productive. But, there are ways (which don't necessarily overlap) a founder could spend "excess" money which don't inhibit drive at all.
Probably the lowest hanging fruit would be to eliminate actual debt (founders may have student debt, credit card debt from earlier in the company, etc.); getting rid of debt probably won't change behavior. Maybe other health-related things. Actually, a lot of this could just be handled as "generous startup perks" vs. payouts; if I knew I could always fly in domestic E+ or upgrade-to-F on my preferred airline, and stay in a decent hotel, I'd be a lot more into taking back to back business trips all the time.
Taking care of someone else's expenses (e.g. kids, parents, or other dependents) probably won't reduce motivation, either. Fixing things which inhibit a founder's productivity (paying for a housekeeper, driver in some cases, closer apartment to the office, ...) seems like a good idea.
It's probably a bad idea to pay someone enough to become an investor, or to buy/build a house (oh god no for BUILDING), indulge in expensive AND time-consuming hobbies, etc.
The gray area is when founders would actually take an outright sale, but are given a choice of $5-10mm now and continue instead; that's enough to possibly reduce drive, but not as much as selling out.
One option might be to put some of the payout into a "lockbox", where it's safe for reasons of diversification, but not accessible. e.g. you sell, get $1-2mm into your 401k, or into an account which is inaccessible (but safely invested) for 5 years. That way, your downside risk is covered if the company tanks, but your lifestyle doesn't change.
Although, anything like this will make Bay Area luxury car dealers very sad. :(