Well, I'm the one in my family with bi-polar and I can tell it from his perspective. Mania is good fun! Everyone else can see that it's not healthy, but he cannot see that - he's just fine and normal, in his eyes. The last thing he needs is to be "told" that he's wrong, or what to do. It will backfire every time and put him on the defensive, creating the angry, irrational outbursts and behaviors. I will also say that it's very exhausting, and even though he may not express it now, he wants help. Deep down, he knows he can't do it by himself, but cannot accept "defeat" and doesn't know how to ask for help.
There are different bi-polar diagnosis - mine is classified as bi-polar I. My mania is triggered by interruptions in my sleep pattern, and I have not experienced severe depression. I've only had two manic episodes and the only thing that got me back on track was inpatient therapy, once for 2 weeks, the other about a week. The solution he may need is dependent upon which type he is.
Even though he's in out patient therapy, it's really easy to "fool" them for a really long time (at least it was for me), until it escalates into severe mania.
I understand your concern and wanting to help, and you should, but very carefully. You didn't reveal your relationship - just that he's a family member. Those closest to him (wife, parents, siblings) should be taking the lead on this, however, if you are a little further removed, you might have the opportunity to provide a "safe" outlet for him.
For starters, please do not go on what others in the family are saying through the grapevine. What happens quite often is that certain people are much more sensitive, quick to judge and blame the illness on any behaviors that they don't agree with. Please make your own decision, based on your own personal experiences with him. Talk to those closest to him to get their feel - just showing your concern and offering help, if they want it. Take it from there - you may feel compelled to invite him for lunch or something, to form your own opinion. There are calm and positive ways to express your concern with anything that you deem inappropriate or destructive. You may do a little reading about the illness to gain a better insight. Then, you may feel the need to call the counselor, but please ask those closer to him first - I'm pretty sure they are not allowed under law to discuss with him your discussion.
One thing I know for sure - it does not get better on its own. Eventually he will "crash", meaning come down from it, but then most likely will sink into deep depression. I know that my family members rallied to get me the help I needed, with my doctors, and somehow got me to admit myself into treatment. I sincerely hope that your family will experience the same success.
If I can provide any more insight, please message me. Good luck!