Why do the points go up every time for a reward when you nearly there

Used to be good app but now not worth it at all better ones out there!!!!

So first was 2,500 then 3,500 up to 6.500 nearly get to that and jumps to 12,500 I'm currently on 12,400 so look to check and now it's jump to 50,000 coins before a £5 reward.

This is really not worth it anymore especially when it doesn't even count all your steps 😡