funding is the main problem

If you are trying to bootstrap your startup, then one of your biggest challenges is trying to find co-founders who can/will put as much skin in the game as you do. Everyone wants you to take all the risks while sharing all the rewards.

For me it is not ideas or building, it is staying focused on what actually matters. It is easy to keep adding features instead of solving one real problem well.

Distribution. You might have best idea and best product. But if no one knows it, then its nothing.

Getting in front and hands of users and making them use your product is the key challenge.

"Why would user choose your product over existing established competitors?"

1. Distribution 2. Splitting time between family, day job, and building the product.