Does a higher education cause having less friends?

In theory, the higher the education you attain, the higher the potential for you to have more friends and connections.

In reality, your tastes in friends may vary because of commitments and personal preferences and that could see a reduction in the number of friends - though the quality of your friends should improve to offset the reduction.

No... arrogance does

There's no correlation at all on a 'personable' level! The only thing that MAY influence that appearance is social visibility, which instead of being a social butterfly, an educated person may have a focus for their attention on projects that require deeper thought and thus less time for partying. Conversely, think of those people who go to university and graduate with qualifications that show their ability to learn, but who do not put their learning to use - they have the 'higher education' but just not the focus to use it - yet either they or the 'focused' person may have many or few social friends.
Thirdly: What is a 'friend'? - someone to party with or someone to trust?

Ppl with lofty goals usually don’t care who’s head they stand on to get there..

While in school, some programs can be very isolating. Your classmates are competition for research or grad assistant positions.

I think that the pool of people you talk to in general gets smaller after you graduate. The connections are professional that may or may not develop into a social relationship.

Not in a "normal" situation. A higher education might cause a person to have fewer friends if they live in an area where most people are uneducated. It would be difficult to find common ground to share ideas.

No. There are too many other factors that can influence one’s social life

I think it is the opposite.

idgaf about friends if I I had a PhD lmao

Mostly use for their own benefit.

No.