They buy it based on whether the game is good or not, and respec would objectively make it worse.
Is your game worse because you can fix a character built around thrown weapons or spears?
Is your game worse because several spells are in the wrong school, and you now you can't cast them?
Is your game worse because you got +120401 to Hit and Damage, and want to fix it? (This is a real bug)
Is your game worse because you are having more fun with respec than without it?
The answer to all of these is "No."
Let us examine them one by one.
Is your game worse because you can fix a character built around thrown weapons or spears?
You chose to build your character around thrown weapons or spears. You. Not anyone else. Therefore, in other words, you fucked up. Congrats! Welcome to the human race! Fucking up is what we are experts at. But here is the thing: Well adjusted, mature human beings accept responsibility for their fuck-ups. They live with their fuck-ups. They don't throw a temper tantrum and demand that that everyone else pay to fix their fuck-ups. They don't blame everyone else and insist on collective guilt and that everyone else pay reparations for their fuck-ups. You fucked up making a thrown weapon or spear character. Take ownership for your fuck-up and live with it,
motherfucking basement dwelling shithead! So, yes, respec shouldn't be allowed for this reason.
Is your game worse because several spells are in the wrong school, and you now you can't cast them?
If you are saying that the spells are put in the wrong schools because of a developer mistake, then yes, respec shouldn't be allowed. Get the developers to fix their mistake.
Stop enabling incompetence, fool!
Is your game worse because you got +120401 to Hit and Damage, and want to fix it? (This is a real bug)
See the second question above.
Is your game worse because you are having more fun with respec than without it?
Go play storymode, then, dramafag.