I agree that BNB has significant growth prospects in the long term, given the speed with which the Binance project is developing. But I do not consider BNB to replenish my portfolio, because its price, for me, as a small investor, is already very high today. I'd rather buy MATIC, which is more likely to give me a double profit over the same period.
BNB is a safe investment and an in individual who wants to just park his money and play it safe can invest in BNB and just leave his wallet in safe place. But for the ones who want to make it big they shouldn't invest in BNB as you said the price is already high, chances of it exploding are pretty low as compared to other low value tokens that can make one rich in a small interval of time.