Is it worth upgrading this computer?

I would like to know whether it is worth upgrading this PC or buying a new one. I would love to play Fortnite, Gta V and Frarcry 5 at 144 fps on Full-Hd. At the moment I have the feeling that the Cpu is the weak point in my current PC, as it is almost always 100% busy. The current system is:

Nvidia GTX 1060 6GB

i5-6500 CPU 3.2GHz

It will be more because of the graphics card upgrade with the new 3000 series but it is difficult to say whether it pays off in upgrading because you have not written anything else, e.g. Which power supply mainboard ram etc.

You can get the 3070 for relatively little money when you get it

And why 144Fps do you have a 144hz monitor?

I don't know where I can see which power supply and mainboard and I don't have a 144Hz monitor but I want to buy one.

Ok yes until you don't have a 144Hz monitor you don't need to worry about 144Fps but if you have to worry about the 3000 models of graphics cards if the money is still there I would recommend an Amd Ryzen 5 3600 then you need a new mainboard ( 100 euro) so probably for everything together is then at 800 euro

How much GB of ram do you have?

No matter where, one of the two always slows you down - so you should see if you can get something for your hardware & assemble a new PC. If necessary, you can keep the housing and power supply.