Key is that the mentor is 'an experienced entrepreneur'. This is very important - everywhere I see nowadays are startup programs with 'mentors', most times they are just corporate employees with no entrepreneurial trackrecord.

What do experienced entrepreneurs know?

Their advice is initially ignored and they know that that's normal. Every first-time entrepreneur has wrong assumptions that they are advised against. But they just must test them out themselves. Non-experienced entrepreneur mentors want their advice followed and quickly give up mentoring if it isn't so.

That advice is still very important: the advantage is that you get to a point quick where you remember the advice initially ignored and pivot faster and learn much quicker.