always allocate investment in new coins smaller than your investments in high ranked, reputed coins like btc and ethereum, it's simply basic risk management that despite the fact that your saying is true, still 90% of altcoins could be losing their value easily.
even though it always comes back again with your capabilities of choosing best project out there.
you just couldn't always accurate in your investment so it's better to be safe than sorry, after all even coins like bitcoin and ethereum isn't lacking ROI as long as you have the sufficient capitals to invest in them.
Tough call with new project while with established assets, there's always a good run if you will invest your money with a project that already gain massive support from community and business industry, you just need to find and sort all those projects if you are keen to succeed from this investment venue.
Not easy, but you can do it with good understanding and knowledge regarding to the business/investment that you will going to support, to the extent of investing with new projects that you truly believe and trust.