asking for an opinion

I will just ignore them

It wouldn't bother me at all. I've worked with many different types of people.

If I worked with people who are young by age but old by their behaviour, I would leave them alone.

If they are older but have a youthful outlook on life I would regard that as a real positive. If they were simply immature then that would be a challenge.

That would be a tremendous challenge and a task for me to work harder. But if these older people but are infantile in their attitude about work-- and nothing productive is done, therefore, not benefiting my life there in the company-- I will resign and find a better job that I will be very happy with and be successful.

that depends....how is their behavior impacting the work environment?

I just don't want to work with anyone irresponsible. It's why I left one of my jobs.

of course its a challenge