Moving to Coingecko is a choice and "trending" doesn't translate to top-rated overall, Bitcoin is the best. Though strange, Bitcoin may not be in the 100 trending position everyday, especially this time that it's selling.
Bitcoin is always trending as long as we are not in the beat market. Inflow and outflow in bitcoin is far greater if compared to those of altcoins (shit coins). The trendy is just used by Coinmarketcap to make money from developers to let people easily see their shitcoins on the site. Later the coins will dump and many people will lose money that expected.