As far as I understand Monero (and perhaps Aeon) are the only anonymous coins for which anonymous transactions are mandatory which means that only 1% of all transactions run on the competitors (Dash, ZCash, Cloak) have anonymity enabled which in turn makes them very unsafe because they could be much easier tracked. So why do people invest in them?
Did you remember if the bitcoin already pseudonymous coin? But that's not mentioned by you. The privacy is only a good reason to invest in them but there are some technical improvement from the bitcoin itself. You can try to take an example such as Zcash. Some said that zcash just another fork but they forget if that already got improvement.