Why do I have to pay an extra subscription?

I already paid $20.00 for the game and I don’t understand why I need to pay a monthly subscription to be able to play with other people. This is a multi billion dollar industry and I don’t understand why you need the extra money. Minecraft is already making so much money from people just buying the game and now we have to pay even more to be able to play with friends. I was so excited to be able to play with my friends on the game and then I realized I had to pay an additional monthly subscription. Please fix this and maybe there will be millions of more people playing it because they’re able to with having to pay so much extra money. Sincerely- Minecraft player who doesn’t have the money to pay for a monthly subscription.