> In my position, would you encourage your child to chase their dream? Or would you be comfortable telling them every few weeks until they gave up that you don’t think they should be a vet?

Can't you do both? Let her know about the serious downsides (perhaps don't "repeat every few weeks until she gives up") and if she chooses it anyway, encourage her. This is her decision to make, not yours. She will be responsible for the consequences, not you.

She’s 8. She’s not responsible for much of anything. She’s not mentaly capable of being responsible for making future career decisions. If she said she wanted to be an authoritarian dictator, I’d crush that dream fast. But she wants to help animals. And being someone that she looks up to, it doesn’t take much for me to crush a dream. So do I start crushing that dream now (her wanting to be a vet comes up weekly, so either I would ignore it or have to keep reiterating my position), and ruin any chance of her becoming a vet, or do I let her invest years into it before telling her I think her career choice is a bad idea?

At 8 years old I'm not sure what the downside is to waiting a bit. It's not like she's accruing vet school debt right now.

Late reply, but:

> She’s 8. She’s not mentaly capable of being responsible for making future career decisions.

She's 8, she doesn't have to make future career decisions yet. When the time comes, it's her decision to make.