I will tell you for free that every altcoins is design in one way or the other to sort for funds from the public. This is the mechanism put in place to make you believe it will yield positive result at the end.
My observation
The owners of altcoins have one thing in mind , to catch out from your invested money on there coins and start up a new business or to support their existing business or to invest the money on bitcoins itself. So it easier for them to pull out the money from the exchanges forcing the price to hit zero.
If they have good mind , they can pump in money later when they have made profit from the business. If the business collapse or target not met, the coins automatically die.
No matter how promising an altcoins can be , bear in mind that the owners has his own reason for creating them which might not be made known on the white paper. If it is not bitcoins , stay away from shit coins with hundreds of empty promises.
When it comes to crypto investments, or any investment at all, risk management and proper research is key. Though Bitcoin might be the most secure and established of cryptocurrency, I wouldn't say all altcoins aren't worth investing in. Some are definitely overhyped and are built to fail but some are actually really good, solving real problems, and have really strong use cases.
So, it all boils down to proper research. If you want to make an investment, it's best to invest in Bitcoin though, but if you want to diversify your investment, then make proper research.