Well, if you have some other revenue through some full-time then any time horizon is fine, but is it really fair to put yourself in the same type of conversation as your competitors who've raised money?
Cockroaches are also likely to survive all sorts of catastrophic events, yet we don't think of them as somehow competing with us.
I'm not trying to engage in a battle of wits. I'm just saying that there is no win for you by outliving these competitors. The idea for you (I hope) is to turn your business into something that can be your main business and not something you do on the side "just in case".
If you think in terms of ROI, how long are you willing to keep working on this without it being profitable? Ok if you say "5 to 10 years", but if you say "as long as I can", then this is not a venture, this is just a nice hobby.
