Maybe I think for him to draw merits to himself, the write up should be more organized and how he goes teaching than just slicing it short and it looks very confusing and not true. Before convincing people to invest in bitcoin there are some certain things they must know because whatever that happened with the investment he would be hold responsible because of convincing he did.

So for my advice is that teach them the whole concept of bitcoin, usefulness and important more especially the security aspect of it then let them learn to read more content the relates with bitcoin to build their faith and belief towards bitcoin before finally making decisions to invest in bitcoin at this point you may see that everything is in line and whatever that may come of it they are already aware of the risk associated with the investment they are about to venture into.

I think if he is aware about risk and how market reacts to different conditions then it's all right but just want to ask that whether this amount is too big for him? As you said his salary is $400 and he invested $500 in btc which sounds big for him so you should also tell him invest savings but also have in mind the rule invest what you can afford to loose.You should also tell him not to panic in small dips and beleive in long term holding if we wants actual returns.

there is nothing wrong if you provide input to your friends because from the start you and your friends discussed bitcoin issues before, but never force your opinion on your friends because 100% of the decisions return to your friends all the risks he will accept after investing in bitcoin

Investing more than salary is not a problem because OP didn't mention whether his friend invests with salary or from savings, as I believe everyone will have savings. Moreover, he only invests once, so it will not be able to affect his daily living needs. I am more interested in whether OP's friend understands the risks of investing in bitcoin? I don't believe anyone could fully understand investment risk in just a few sentences in that brief conversation. I feel OP's friend is investing hastily without any knowledge, too risky for both.

I am also a Bangladeshi citizen and I have also invested in Bitcoin. Many people have invested in bitcoins in our country keeping the privacy. Bitcoin is illegal in our country but we get all kinds of benefits. On the one hand, we have benefited a lot because we don't have to pay taxes to the government. I think it's better that Bitcoin is illegal in our country. We will invest with confidentiality. Bitcoin will be legalized in our country one day.

Investing is already taking a risk, so probably right after you mentioned to him about bitcoin, he has started to educate more of himself before he was finally convinced to invest in it. Good thing you mentioned to him and made him aware that bitcoin is capable to make him lose more than profiting, at least he won’t dare to blame you when in the future bitcoin price will start to plummet and drop its price sharply. But I guess he’s already aware that everytime bitcoin drops, there’s always a chance after for recovering.

That is the best case scenario, in my experience most people never consider things not going their way and then when they inevitably find a setback they are incredibly surprised this took place, however instead of taking a moment of introspection and devote some time to the task of finding out what is exactly what happened, they prefer to blame someone else for their problems, and in this case the OP will be the perfect candidate for this on their minds as they were the ones to introduce bitcoin to them.

All you do is tell him about bitcoin. Everything about it. Advantage, disadvantage everything. All you do it put the food in front of him. It has to be his own decision to whether to eat it or not. Because the moment you push someone for eating, they are most likely to vomit afterward. Same with bitcoin investment. What you did is alright, but you should have told him to wait a bit longer and process the knowledge. Because when they take a decision in a hurry, they will most likely blame you later on if things went south. But it's ok as you have explained all the risks already. Now you should tell him to learn more about Bitcoin. Because there's no limit in learning. Cheers.

It is a very good thing to recommend him to invest in Bitcoin. After investing, he also needs to know how to protect his investment. Which exchange did he use, is there any information about any wallet? One of the best favors you can do for your friend might be to introduce him to this forum. I recommend this to you.