Since the dawning of the early 2000's people have been emulating old games by utilizing bios from older systems and play roms called .isos which are copys of the original game disc. There's been some controversy over the years, so let's get into it.
Cons
The cons of emulation is that it can land you in hot water with game companies like Nintendo who will try to sue you and the manufacturer of emulators. Like what they did with Dolphin Emulation. Long story short; they tried to put an emulator in Steam's library for the Steam Deck, Nintendo didn't like that so they slapped Dolphin Emulation with a court order to take it down and I believe are in the midst of suing Dolphin. Now the con of this is that if you use emulators then you run the risk of being sued yourself which would cover a hefty fine on top of hiring lawyers.
The other con for emulation is running the risk of getting hit with a trojan or a virus. Which if you don't know how to get rid of can be costly if you choose to get another computer or laptop.
Pros
The pros of emulation is being able to play the game on your computer from a system that you no longer had. With each new console that comes out, game companies like Nintendo and Sony have done away with backward compatibility of old in favor of consumers purchasing games that may have already had in the past and being able to play it on the new system. For the consumer it can be just as costly as buying the older system and buying an older game.
Having emulation on a computer is more cost effective and it's convenient for people to utilize whether it's for streaming or just taking their laptop on the go. Plus you can have all of your games readily available to you. For consumers it's more about preserving the memories of the past and being able to play games. It's also about enticing the newer generation to get into those older games and foster a community.