Yes it is true that such promotions or advertisements can make bitcoin prices decrease and decrease public confidence in bitcoin, and yet I would not think their coin would replace bitcoin.
It is affecting the prices for sure because they eat up the market share. Replacing bitcoins is out of question till they develop something really unique.
Basically, it is about supply and demand. Now demand is affected by a huge number of factors like news related to crypto, laws in countries and other things.