There are obviously two schools of thought here, but IMO a founder who is at least financially comfortable will make better long term decisions and take actions influenced less by personal stress.
I think there's two important timeframes to consider here.
You need to be "financially comfortable" for the 1/3/12 month foreseeable future to be able to fully focus on your startup.
I'm a lot less convinced that being 10+ year financially comfortable is necessarily a desirable trait for a founder. Knowledge that their future financial freedom is 100% dependant on the success of their startup is possibly a stronger driver of "better long term decisions" than someone in a position to think "it doesn't matter too much - even if this fails I have a contingency plan"...
(And I say that as someone who was once part of a team that rejected an acquisition offer that would've meant a half million payout to me, because we believed at the time we were going to be worth at least 10 times that within a year. And we were wrong. But I still stand by that decision at the time and would make it again in the same circumstances...)
