Money can help you do the right thing faster if you know the right things to do. Otherwise raising and then spending money a little better each round can end up in focussing on the investors as being the customers of your business. If you consult at a medium-high enough level, you can probably raise a fair amount of money yourself and self-fund.

It really depends on the app and if there's market demand ($) for it beyond just users.

If it's the first app, learning how to make money is more valuable on a smaller project than building something big and having less of an idea.