Yeh altcoins is safe for investment but there is one thing which would you set in mind that if you want investment in altcoin then you should choose the top 10 altcoins of CoinmarketCap.
Because they are trusted and real his team are real not fraud those reason put the project in list of top coins of CoinmarketCap .
But if you buy rather than that then there will be 99% chance of fraud so be careful
For long term hold choosing the top 10 is a good choice, But if you want some true profits you need to find a hidden gem in low market cap cryptocurrency. that is the place where most money is made.