Finasteride is not a new drug. People take 5x the amount per day for prostate issues than people take solely for male pattern baldness. Think about what 90% means - 9 out of 10 men. We would have seen that plastered everywhere for decades by tens of millions of people.
That dermatologist even talked him out of using minoxidil. That dermatologist was like, "I just accepted it and I shaved, so you should just shave it too, bro."
I hate misinformation. This goes for every topic. Making decisions of what to do about hair loss is hard enough without random people fear-mongering every product that we have or projecting their own negative experiences onto others.
Even though I've been taking finasteride for 11 years without any issues and I don't know anyone in real life that has had any issues with taking finasteride doesn't mean that I ignore the possibility of side effects.
It's times like this that make me appreciate that I had a honest and knowledgeable dermatologist when I first asked about hair loss solutions.