mecheng123

Most people watch big tournaments and/or high level competitive players (LoL, Dota2, cs:go, SC2). LoL and Dota2 run tournaments with prize money in the millions and the competing teams are fulltime players that live together and have coaches and sponsors, etc. Imagine Messi (or some American star athlete, eg. LeBron) streaming his training via a GoPro. Fans would be very interested.

Single player / non-competitive games (such as your example, Fallout 3) are indeed much less exciting and get less viewers. There are also streamers that aren't very good at playing anything, but they're entertaining in one way or another and have built up a following that just watched them play whatever.

That is the maximum score. You can play on, but the score is capped there.

All of those. Gaming has been steadily growing for a long time now and has reached a "major player" status, so the timing is good. They're obviously a very skilled group of people. And finally, great achievements require some luck.

It also depends on your location. From what I read/see American developers all have macbooks, but I'm currently attending a high tier Western European uni and there hardly any macs at all (only professors that came here from USA have them, lol). The CS program here uses Windows & Ubuntu.