Buying a banner, you have no control whether ten different people see your ad once, or one person sees it ten times.

A mistake I've made is investing in my idea rather than the entrepreneur's. Sometimes I'm excited about an idea that is similar to the entrepreneur's idea - but not the same. A smart entrepreneur will convince me it is the same, until I write a check!

There are lot of ways people get non-economic payback - learning, networking, and relationships. These drive most angels more than the money.

Crypto today is a libertarian paradise. If you send your money to the wrong place, it's gone. If you send it to a merchant and don't receive the goods, you have no recourse. This is cash. Treat it as such.