I think this is worth it if you would be a good co-founder in any case. That means you are really putting in 8000 for not working the first two months, and then work the same amount as the other founder.

However if putting in 8000 is the only thing you do, then it's a horrible idea. Putting in more money, maybe.

This is the perspective of someone in the Bay Area though. 5000 is easily saved/spent here.

You can find someone else cheaper, but likely would have to communicate remotely. That increases your risk too.