For me, and probably for most, it's not a matter of quitting your job in order to work on your "successful" startup - if it were already successful then there'd be no issue at all. Rather it's about quitting while the startup is just beginning to look reasonably good, _in order_ to make it a success.
Since I've been working as a mobile developer, and also management consultant (my other career), it's always been extremely easy for me to find a new job whenever I needed, so there has been very little risk involved.
Still, it did require some savings, since our startup is very research intensive and will take several years before we see any revenue. We secured some basic funding now though, and things are looking good for the next stage too so I will only have needed 6 months or so of buffer.
In summary, my view is that if you're a reasonably skilled engineer or have some other attractive occupation, there is nothing to fear. The worst that can happen is really that your startup doesn't work, you'll go back to what you did before with a few months of missed income but with plenty of useful experience.
I don't think there are many situations or cultures where a failed technology startup attempt on your résumé would count against you in any way, in most places quite the opposite.