told me I was stupid for paying off my mortgage in the late 90s. Instead I should have done a refinance and used the proceeds to buy front loaded tech stock funds from his bank. The only winner would have been the advisor's bank account from his commissions.

I didn't take his "expert" advice. I did invest regularly with money I earned in low fee index funds and bought in both boom and bust markets. As I got older I moved gradually to a more conservative balanced portfolio that includes bond index funds.