Ultimately, equity math is less about math and more about psychology. Startup success is binary so the fine details of the split end up not mattering at the end

Ultimately, equity math is less about math and more about psychology. Startup success is binary so the fine details of the split end up not mattering at the end of the day. What's important is that the process you use to assign equity leaves everyone feeling it was more than fair. You could start with a team of talented people and arrive at the same equity numbers via two different processes and one will result in a billion dollar company and the other a million dollar company because the founders are motivated in the first and discouraged in the second. What's ideal is that each founder believes they got way too much equity and is glad to be a part of the team. Put in that perspective, dicking over 5% isn't something that should be encouraged. This is why founder chemistry is so important. If you're considering co-founding a company with a person, run this hypothetical in your head: You have both just sold the company for a billion dollars and you get 70% of the sale and they get 30%. Are they happy that they're now worth 300M and even happier than you're worth 700M or are they jealous that you got the way bigger share of the pie than they did? If it's the latter, run away immediately, there's no good outcome possible there.