One problem can't solve from first, if new investor can't trust new fresh coin why they don't invest in old coin. We several good coin already exists in cryptocurrency even with very low price. Even I don't think there could be a trust problem. All solution is now is the correction time!!
Some old coin should die to build new coin. Very very low idea was getting success in 2017, so investor has interest in new coin for good profits. Top coin need correction time to break last top price. Supply is also a problem, release more coin without any time limit when marketcap is getting down.
old coins do not have to make new coins to be expensive they just need to need a good development that can trigger traders to buy coins so that the price at the exchange will increase in price because more will be interested and will make the price go up.