Their mind is still programmed with beliefs that serve their outdated goals. It’s difficult for them to believe that your new endeavor will work out because all they know to be possible is what they’ve done.
Such is the risk of limiting beliefs.
"He who looks for external validation is not properly grounded in life." -- Marcus Aurelius (20 June 2024 future edit, this must be Epictetus)
In other words, do not care about what others think... Heed their advice, take it into account, but ultimately you must make the decision yourself.