In order to be the hunter horn man your friends want you to be, you must learn how to play hunter horn like a guitar hero perfectionist.

Get a feel for your combo list- perhaps trying them out in training room or if you are cocky just go fight kulve taroth solo (do it, I know you wont)

Now that you have learned your combos, you can now apply them.
Call over your friends (random strangers) to do some quests with you, maybe fight some easy monsters like great jargras, deviljho, those fish things no one really remembers and xeno'jiiva.

Just remember you are there to help your friends not lock them in a fenced off area in the arena while you watch your friends perish to azure rathalos.

Now it's the real test all hunters dare to take.
You must fight arch tempered nergigante in 5 minutes. SOLO
If you cannot do this with your hunting horn, something is wrong. Perhaps read step one again.
If you cant seem to get the hang of this, remember, use SOS flare or ask that one HR 78 person to join you.

If you have gotten this far, then I congratulate you. You are less than 2% of the MHW gaming community. You can tell your friends to jump in the rotten vale for doubting your adamant nature of the way of the horn. If they get carted, then it's their faults. I'm looking you greatsword users stop jumping in front of the xenojiiva beam you fricks you cant block lazerrs also say hi the the handler on your way back to camp will you
????

Kulu hopes you like corn chips