Mining it is an option, which isn't really feasible depending on your environment and resources but it's one of the ways you can earn it.
Trading is another option but it takes intellectualism to get this done in a very good manner and earn profits to purchase bitcoin
Rendering your services also and getting paid in bitcoin is another option to consider
Mining isn't an option, you'll need specific miners in order to mine, using your own computer won't just do it. On top of that, you'll need to do a cost to benefit analysis, due to high electricity costs.
Back in the day there was a faucet where you could solve a captcha and earn up to 5 Bitcoins per day. Wish those days still existed lol
While I remember the early days of Bitcoin (2013-2014), you could potentially earn a decent amount of BTC, I believe that the amount you're claiming is an exaggeration. Faucets were my first experience with Bitcoin and accumulated a decent amount for today's standards.