I agree some projects are great fits for single founders but you should be able to convince at least one rational person this is a good idea and is worth invest

I agree some projects are great fits for single founders but you should be able to convince at least one rational person this is a good idea and is worth investing the time, energy, money into. It doesn't matter if that person is your spouse, a co-founder, an angel - but make sure at least one person whose opinion you respect and has something to lose if you fail/waste your time thinks this is a good idea.