Why? Well picture this, your laptop is 3 years old and it can't handle any more games. And it's also low on memory.
How to fix this? Er,,. all you can do is buy another laptop.
What about your desktop? It's 3 years old, and it also is bad like your old laptop. What to do? Well, you could upgrade it. You can buy a new GPU and new RAM and maybe even a new CPU. That could cost around 500-600 dollars and you got a high end machine, or you can buy cheaper stuff and not go for high end but whatever.
Your gaming laptop costs 1000 dollars, so does your desktop, monitor, keyboard and mouse included. Your destop can be upgraded over the years until you need a new motherboard, which would be like 5-6 years. Depending on what you want, the price for upgrading will probably be cheaper than buying a new laptop