It all starts with the framerates. Lets say you have a GTX 950 and a Pentium G3258, you play games at Geforce Experience sertings and always get 60fps in games even if its at lower setting. But one day, one day, you start playing a AAA game, like Witcher 3, you cant get 60fps for some kind of reason, so you start OverClocking your GPU and CPU, but discover that you GPU brand (Asus for example) OverClocks like shit. So you get a GTX 970 to play AAA games at 60fps lock. But now your CPU is bottlenecking your GTX 970 and you get an i7 4790k. Now you are getting above 60fps on all AAA titles on you 60hz monitor, but for some reason, you discovered G-Sync. Now you have a 144hz monitor with G-Sync and 1440p resolution. To match the 1440p/144hz combo, you OC your i7 and your GTX 970 to max clocks. Now you are all fine and dandy. But now you have overheating problems and your CPU/GPU are throttling, so you get a custom watercooling loop with 2x 360mm rads.
Now you want 4k resolution and textures, so you get 2x 980Ti s and an i7 5960x all OCd to max.
And thats how you go from an entry level build, to Enthusiast grade PC in less than 3 years.
Welcome to the master race.