I live off of Bitcoin, and I still don't understand how it works

Hello, I'm not used to this site so forgive if I get something wrong. But I did read the rules.
I'm not an "internet guy", my son showed me Reddit some time ago. I didn't give much attention to it, it's not my kind of thing. Today I opened it again and found out there is a community here about Bitcoin.

My story is that I "bought" it when it was cheap in 2013. I was selling my car to a friend of mine, he didn't have all the money to buy it, just a part of it. He asked me to split the amount in installments. I declined, I don't like installments. Then he asked if he could pay for the rest of the value with his Bitcoins.

He explained for a long time what it was, and why it worked like money. At first, I didn't like the idea. But I wasn't needing all the money at that time, and he said he could buy it back. So we did it.

He teached me to use it though I didn't really used it for a long time. It was just sitting there. Of course I heard the news that it was getting value. This same friend told me to buy a physical wallet to hold it. He said it was more safe, and I agree. I also like to have something that is not just in my computer.

In the last years, I retired earlier. Every month I sell some of my Bitcoins to this same friend. Not any insane amount, just what I need for my family expenses etc. And sometimes some more when I need to buy something new.

I don't live a live of luxuries. I have a good house, a good car. I pay for my children college and school and we do some family travels together. And I guaranteed they have a house to live. That's enough for me

That's it, I'm not in any Bitcoin related community or discussion. I don't know how it works. My friend tried to explain me a lot of times. I know enough about it to use all these years. I know how to send, how to receive and I have my pass phrase in a paper well hidden.

I read about how you guys buy and sell it all the time. I'm not any specialist and I might be wrong. But maybe you just need a little more patience. It took a long time for my Bitcoins to be worth something.

Excuse me if I don't reply you. As I said, I don't really use Reddit
Also excuse me if I made any grammatical errors, english is not my first language and I don't live in an english speaking country.