VCs really don't care about "sweat equity" or "discounted salary equity". They believe that if you don't bring actual cash to the table then you aren't risking as much as them (even though they are only putting their clients money, not their personal money in most cases).
That's one reason I didn't have trouble bailing on a startup I helped start. We took in $1.5mm, did some things poorly (such is life but learned good lessons from them) and even with a path forward we would have still required some more investment (since we weren't profitable). Therefore I knew what the current liquidation preference was, I computed what another round's liquidation preference would add, and it became clear we'd have to sell at $30-50m just for me to start getting money.
The likelihood of that happening was small, and the feeling of being un-incentivized from selling at a respectable $20m made me realize the whole game was stupid and rigged. Now I work at a bank making almost 3x of what I made in hard cash (plus better benefits which equals hardware) and that extra money is giving me much better returns in my retirement and stock accounts, and a better quality of life (and less stress).