Why do individuals in the military get mad when you tell them you are getting out and going to college?

I totally make sure that the individual has a plan when they get out. Just going to school isn't really enough, and isn't thought through well enough, My biggest concern is that I don't want them to be one of those guys on the side of the road with a cardboard sign that says "homeless vet". To answer the question as asked though, is someone joins the military for even just four years, get all their training, GI Bill, skillsets, etc. and bails, they have still done more than like 98% of the rest of Americans. Any amount of service, if honorable, is commendable. The military for life isn't for everyone and we should be ... aware of that... at the very least.

Whether the appeal was well intentioned or a form of chastisement, the 'counseling' somehow came across as a negative; the COC should not wait until the last minute to do career counseling, or to assume the SM is going to reenlist or get out. Everyone knows when a SM nears separation and should start early to encourage the good people to stay on. No employer likes to lose a good employee esp if they have an opportunity to say something to s/he. If the SM has made up their mind the least we can do is wish them well and let them know their hard work was appreciated - thank them for their service.

That is an individual mindset. My original plan was to enlist for one 8 year term. I chose to be a Medic, instead of having to choose from the options given by my ASVAB score. Majority of my service was at Ft. Drum, NY with 2 deployments in OIF, getting extended during the second one. Then I did a short time in a NG unit in my home state.
A few people at my unit, asked why I was getting out and I gave them my reasons. No hostility, though with some, I could feel a push from them; trying to urge me to re-enlist. I re-enlisted in the NG back home and I guess that seemed to satisfy the people that asked.