I used to read biographies, I stopped, cold turkey.
3 main reasons: Survivor bias, confirmation bias and silent evidence.
Every time I read a biography I would ask myself how many other people did exactly the same (or better) as this person but failed? Did in this case means “did what this person attributes as key to their success”. The answer became clearer, you can work hard, persevere, get degrees, etc. and still FAIL. What people attribute for their success is not necessarily what they say, sometimes correct timing, right city, right person, correct decision at a specific time etc. play a much bigger role.
So as a rule, I don’t listen or read what someone attributes for their success, I observe. Actions speak louder.
I also try to read as many anti-biographies, i.e. people who don’t like the subject and write about the person from a negative point of view, you learn quite a lot (although you have to read between the lines as the authors get carried away). E.g. The “anti-biography” of Marcelle Reich (March Rich), Founder of Glencore. You learn quickly that bribing and being a cowboy in the natural resources business is the best way to win, whether you like it or not. Compare this to if Marcelle Reich wrote his own biography, he’d wax lyrical about hard work, negotiation/persuasion skills (in this case code for brown envelope skills) etc.