Bitcoin is a great investment, because the value will continue going up in most situations.
A lot of investments only have the value which people give them rather than solely based on how useful it is, but Bitcoin is very useful. It's going to become more popular.
Problem with non Bitcoiners is that they don't realize what Bitcoin is capable of. They mostly don't even understand the basics, but still think to know that Bitcoin won't survive for long. It's ignorance from the highest levels. Let them say and think whatever they want, because at some point they will look back and regret not having taken Bitcoin seriously while it was still a tiny dot. Same basically was the case when Bitcoin was about to break through $100 for the very first time. According to various "experts" $100 was the ultimate top price for Bitcoin, ever. After that it would only drop in value due to the "hype" coming to an end. Look where we stand right now.