I told him that the day our government will announce that BTC is now fully legalized in the country, I will throw a big party to host all the bitcoiners in my environment to join me to celebrate.
You can celebrate, but a party sounds very unnecessary to me, why will you want to host all the people into bitcoin in your environment, do you have any idea how many they will be and what it will cost you? A big party like you have described will involve a lot of expenses for music, food, drinks and decoration, all these are unnecessary expenses, money that can be used for better things like even buying more bitcoins to keep. Do not let your excitement make you make regrettable decisions.
I guess there's no problem celebrating a big party like what he wants as long as he have the money. Practically thinking yes it is so much expensive and he needs to spend lots of money. If he is a multi millionaire and thats how he celebrate things such as btc being legal in their country why not right? Think about rich people in your country they do big party event when something good happen to them like winning or anything good. Its expensive but the memories they make is irreplaceable and they know they can gain those money again that they spent for the party.