Why Am I Overthinking Career Advice from People I Don’t Even Respect?

I recently ran into a former schoolmate who used to be arrogant and narcissistic. He’s now pursuing a BSc while I’m doing a BTech. Despite not being in engineering, he confidently gives me advice about my career, suggesting I pursue a PhD or follow AI and simulation “gimmicks,” claiming they’ll guarantee success, even though he doesn’t seem to understand that higher studies like a master’s or PhD are typically for those genuinely interested in research.

I’m in Civil Engineering because it aligns with my interest in real-world projects, and suits my long-standing strength in drawing; I’m also open to pursuing a master’s abroad. Meanwhile, another acquaintance who failed JEE twice looks down on Civil Engineering and insists Mechanical is superior. What’s really bothering me is not their opinions, but why I’m overthinking the comments of people who I don’t even respect in the first place.