Maybe having a partner, even one with a low income, helps.
We gave each daughter a budget for their undergraduate studies. They were told that if they graduate from a very good university under budget, they have whatever is left for graduate school or other purposes. One daughter is on track to graduate under budget with money left in her 529. She gets to use it if and when she wants to. She does have vague plans to eventually get a master’s.
Other than that, it is a tough call. There are some graduate degrees that are very worthwhile but that typically do not get funded by the university (such as a master’s degree in the US, or MD, or DVM, or …).
After paying for private HS and undergrad, we invited our kids to experience the joy of paying for their own grad schools if they wished to pursue their Masters. Both worked went to work right after undergrad.
Goskid 1 decided to get MBA in an executive evening program while continuing to work full time. She and her hubby tightened their belts and footed with bill themselves. We gave a generous grad gift.
Goskid 2 went full time MBA program after working a few years. My H almost had a coronary when he heard about education loan rates Goskid was facing. So the Bank of Mom and Dad gave him a loan at much more favorable interest rates. Besides his monthly payments, he also attacked loan, paying it down by $15K. Then covid wiped out his job in April. Had he taken other loans, we probably would have had to help out. Luckily, we could afford to suspend the loan payments to us and he has not asked us for any help. And he starts his new job Tomorrow!!! Will let him have a few months to re-build that emergency fund before he resumes paying his loan.