This game, must've took 30+ tries to get 50k, but I achieved it earlier today. Once I got it, I realised that I didn't get it earlier because I was moving around too much. I'd have ideal positions where jumping I wouldn't get hit by the spikes, but I kept moving because of nervousness. During my winning run I decided not to move from spots where I'd live for extended amounts of time and got 50k. Think I had two lives left by the time I got it too.
There were plenty of times where I thought I was gonna die by the spikes, the t-rex would be so close to them, but I only died once before reaching 50k and it was because of a laser.