This is a really good question, because it seems counter-intuitive to invest your money in other people if your own business needs funding. Here are a few motivations:
* When an angel invests 30k, I get value beyond the cash amount.
The angels I reach out to are founders with multiple successful exits, board members of other startups, and have 20-30+ years of experience. I get access to a fountain of wisdom and the person is motivated to answer my emails and take my calls when I'm stumped by a challenge.
I'm not good at EVERYTHING (who is), but I am proactive about getting help when I need it.
* A priced seed round sets the value.
Let's say you own 100% of a fine work of art, which you've priced at $10M. There's just one problem - only you value it at 10M, so there's no anchor for the real-world value. To get a return on your investment, you have to find a buyer that agrees with your valuation.
What if instead you owned 25% time-share of a work of art (this is a silly asset class, just using it as an example) that you and 3 other people price at $10. If you want to realize a return, there are now at LEAST 3 other prospective buyers that agree on the market value of your shares.
* There are more people like me out there.
I make angel investments in under-estimated Founders, because they're often overlooked by the pattern-matching lemmings in the institutional investment world. This isn't charity either; since a fund-raising round is similar to an auction, there are fewer investors bidding and betting on these founders. That gives me an edge.
I also tend to invest in "work horse" companies, not necessarily potential unicorns. Institutional investors have to chase unicorns that produce outsize returns, but I can participate in seed rounds that never raise after a seed or Series A.
There's a fund that follows the same thesis (https://tinyseed.com/) but I don't know of many institutional investors who make these kinds of investments.
* The best time to raise money is when you don't need it.
In the example I gave (6 x 30k @ 1% for 180k/3M post-money for a business earning 10-15k MRR), I have options for revenue-based financing and other kinds of debt.
Like I said, a fund-raising round is like an auction. If you have leverage or alternatives, you can command a higher price.
YC's startups get 125k for 7% + an additional 375k SAFE, which gets priced when you raise another round. If you sell another 15-20% on demo day, YC can end up owning roughly 20% of your company for 500k.
So, all I could think of during the tepid interview was "y'all want 20% of this business, but are acting like you're at the dentist." People didn't even introduce themselves (names) or ask mine. I know this wasn't intentional rudeness, it's due to application volume. The factory-farming way YC operates made me realize I could engineer better circumstances for myself and my business via an angel round.
Hope that all makes sense.