My melanoma started with a small mole near the corner of my eye that grew slightly and darkened. I didn't pay much attention to it, but my wife and law partner noticed it and suggested I get it checked. My GP said it was nothing to worry about, but made a same day appointment for me to see a dermatologist. She also said it was nothing, but did a biopsy to be sure. She said she would email the result once she had confirmation. Instead I got a call from her telling me it was melanoma and referring me to see a surgeon.
It's a little uncomfortable to have a doctor examine every square inch of your body, but worth it.
I am better with hats and sunscreen now, but stories like your friend's are good motivation to be careful with the sun. Don't procrastinate if you notice something that doesn't seem right.
I have a client whose melanoma got into his brain. You don't want that. He's still fighting it, but I know of someone else who only lasted about a month after their barber found a suspicious mole hidden in the hair on the top of their head.