We put windows in our boring grey computer cases and bought blue LEDs for 2 EUR a piece to light up the internals. As LEDs were so expensive we often opted to use CCFL tubes. We put electroluminescent wire everywhere, even into keyboards. We built our own fan controllers from scratch to fit into a 3.5" slot. People payed 200 EUR for PC cases from LIAN LI and Cooler Master just to mod the shit out of them. Watercooling just became a thing and it was hugely expensive, the PC cases didn't have a place for the radiators so you had to get creative with your power tools. We went to LAN parties with our awesome machines, we organized collective orders in our case modding forums to buy cheap LEDs from china. We were amazed by the latest products, like LED fans that flashed the light in synchronization with the fan RPM like a zoetrope, so it appeared to stand still.
We couldn't even dream of a keyboard with individually RGB keys back then and now you get RGB in everything without even wanting it. Mass production has taken over and all the magic is gone. You just buy it and yeah it looks cool, but whats the fun in that if every PC looks the same - thats exactly what we didn't want, we wanted to be different.
Fun times though!