Sorry about what happened to you, of course. It is very painful, and you can't imagine how sad it is to invest even in research, but the results are very disappointing, and I think you are not the only one who experienced it, but many also experienced the same as you, and it's hard to imagine that after research, but the results are not in accordance with the expectations that we want, you are right that not all altcoins are the same and research can be different.
Altcoins are generally risky, and research alone isn't enough for one to stay profitable in trading them, and it also depends on what kind of altcoins one is trading in because even a meme coin or a shit coin can basically be called an altcoin but they are risker by nature because they don't have a purpose or a project backing them up but they are only created for fun based on popular memes or nowadays famous people as well such as Elon Musk or Donald Trump, etc.
So, one's profitability in trading also depends on what cryptocurrencies they choose to trade because their risk-to-reward ratio will differ based on their choices. In normal altcoins, the risks are lower and so are the rewards, mostly, and in shit coins or meme coins, the risks are higher but so are the rewards. That's why, it's important for a person to know all these things before they start doing it. 
For new altcoin projects, I totally agree that what you said about being very risky is a reality and cannot be avoided. That's why many people really don't like every new project that appears, because it will never give a good contribution to its holders. Maybe until now, and it hasn't been able to return to its glory days.
But there are altcoins that have been around for a long time and, until now, are included in potential coins and I think it's okay if you want to invest in them because, so far, they have made a good contribution and have proven to be very good for their holders.