You might have heard of student loans. They can get rather high. You might have also heard about high cost of living areas. Houses can be pretty expensive. Another thing you might have heard about is high mortgage rates.
A new veterinarian with a specialist cert (which requires an undergrad degree, graduate degree, a shitty pay internship, and a shitty pay residency for a long time) will be sitting on $200,000 in loans and make about $200k. Now, if that person lives in Los Angeles and wants to buy a home they are going to have a loan for a million at 7%. Take-home pay on $200k after retirement/insurance/taxes is around $10k/month. Mortgage on a million is $7k/mo. Loan payments on $200k is around $1000/mo. Taxes on that house are about $1000/mo. Right there the take-home pay comes down to $1000/mo to pay for food ($600), utilities ($100), cell phone ($70), car ($300), car insurance ($100), gas ($100) internet ($100), etc. You might notice that those numbers add up to more than $1000.
Sure, that veterinarian who is already 35 years old now after all that schooling can just rent instead of buy a tiny house, but rent still costs $3000/mo in a big city for a small apartment.