Look at it from this point of view; if your employer is so unhappy with you that, even when you’ve shown your skill, he’s unwilling to pay you a competitive amount then it’s clear you don’t really have a future at your current job.
A new company is willing to risk it on you, while paying more than your current job where you have experience. No surprise they leave in a year anyway.
if your employer is so unhappy with you that, even when you’ve shown your skill, he’s unwilling to pay you a competitive amount then it’s clear you don’t really have a future at your current job
This is the crux of the problem - people assume that anyone going to their boss asking for a raise is underpaid. That isn't always true.
When someone goes and finds a new role on more money it's almost always at a higher level. People move upwards when they move on. Matching an offer usually means paying someone the salary for the higher level role to do the work of the lower level role.
If someone wants to move up a level to earn more I've always been happy to talk to them about that. That's not what we're talking about here though.
I disagree with that. If you go into somewhere as a senior for example, it is not unheard of that a year later you can make a lateral move for 20%+ payrises. I've seen it happen many times in my career (obvious caveat that anecdote != data).
If I think some has reached the next level then I'll promote them anyway. No one should need to prove that they deserve a promotion by finding another company willing to offer them that role.
A new company is willing to risk it on you, while paying more than your current job where you have experience. No surprise they leave in a year anyway.