I think the right time to buy Matic was during the launch time as there was huge hype and even I tried purchasing it but it was sold out. There was tremendous hype and speculations about it which might make any mid level crypto user to invest into matic but once it was launched the matic's magic started fading.
You are correct since most of the projects that was conducted in Binance Launchpad just got hyped during its IEO but when the sale is over the value of the coin start to dump its price. also most of the investors in Binance Launchpad is participating for a quick bucks because they knew that the exchange itself has a big marketing strategies that will hype its price for a short time.