My PC is 10 years old and runs perfectly, updated with a new video card and SSD, its fast and has zero issues, I maintain it and don't install a bunch of useless programs. I don't game so I'm sure I could use it at least a couple more years, maybe more. It boots within 20 seconds and webpages load instantly, but I don't game. As far as using a phone for internet activities, no way, I find doing anything on the internet with a phone a painful experience. Its slower, its smaller and typing on a full size keyboard is a luxury instead of finger pecking on a small screen.
'