Always make sure you throw away the old ones and look for new altcoins, thats why new projects always get into the top 20 list on coinmarketcap every bull market, many old projects will fade.
This is the most stupid advice I have ever heard. A smart user always invests in promising projects for the long term... Decentraland for example
No matter how hard you try to denigrate Decentraland, the Decentraland project will show such growth that nobody never dreamed of