Age-30/31. Engineer in the technology sector. Too late?

That's a statement, not a reason. Why is 33 too late to transition into product management? If they can't give you a concrete answer for WHY then I'd take what they're saying with a hefty dose of salt.

A lot of people will tell you the same thing about consulting and banking jobs. However, many of my over 30 classmates are doing banking or consulting for their summer internships. So I guess what people say and what really happens don't necessarily align at all.

When your friend said something, there are valid reasons, although 31/33 is not too old.

Depending on schools, your age may or may not be too old. There are many schools in Europe where average age is 29-31. But is US, average age is lower.

With a much lower class age (and experience), you may have following issues
a. Overall class discussions/case studies may be just theoretical.
b. Placement is a major issue. All the recruiters will come for an entry level profile. Irrespective of whether you are willing to start at the entry level, many of the recruiters will ignore you. You have to find your job through networks and that process is frustratingly slow with slim success rate.

I have quite a few friends in US schools who mentioned these two key issues.

In fact, I am under the impression that for some employers 30-40 would be perfect timing.

Some proven business models prefer to recruit former-technologists into top management positions, because it is believed that hands-on experience fosters the deep understanding that is necessary to make informed business decisions. This model seems particularly common in Japan, and I think it is becoming increasingly popular in the EU. In those cases, specialised finance/administrative training at a young age prepares a person for supportive roles only.

I find it odd that, despite globalisation, business models continue to vary by nation and continent. The differences should not matter because, at least where I'm sat, age-discrimination is absolutely illegal.