Let's say you make 100000 today. They're offering you 75000 plus 15000 (20% of 75000) in equity which is likely vested over four years with a one year cliff. S

Let's say you make 100000 today. They're offering you 75000 plus 15000 (20% of 75000) in equity which is likely vested over four years with a one year cliff. So, you stay four years. You've earned 300000 and now have 15000 in equity. Yes, they may well offer you more equity over time, but you don't know that today. You've foregone 100000 in income (or more), and the 15000 in equity is, in the best case scenario, worth much more on secondary markets, but only if there is a buyer. In the worst case scenario, the company shuts down some time over the next four years and you are now unemployed, out the equity they granted, and the income you've lost. There are better ways to learn new technologies than subsidizing a company with your talents.