Ask HN: What tech mantras/advice are the least true?

Obviously any axiom or piece of advice can be proven wrong given the right circumstances. But are there any oft-repeated nuggets of wisdom that, in your personal experience, have been proven egregiously wrong, or that you suspect are wrong for MOST people MOST of the time?

Please support with personal experience or careful observation of others' experiences - this is not an invitation to just rant or take pot shots.