The percentage of newly listed tokens isn't really that stable and can it cannot be profitable, not all altcoin do succeed and proceed with their investment, although there some who actually succeed and this is we earn most of our coins from. If you are very lucky at the same time you know which altcoins that you can investment then you can make a profit from it. It is not accurate to get a profit from new altcoins but it can be possible, there are pros and cons to it.