[bennyelv]

The biggest cost is your time. You've valued it at 0...

If the startup idea requires someone (or more than one person) to work on it full time in order to succeed then that's not a valuation that is practical.

[jimmySixDOF]

It's better to say: The biggest investment is your time.

Sweat = Equity

[jlbnjmn]

Sweat * leverage = equity.

Time used wisely is an investment, but time used poorly is an expense.

Being able to tell the difference is key.

[bennyelv]

That’s only a practical way to think about it if you have enough other income to cover your expenditure. Equity doesn’t pay your rent.