there is a difference when you want to buy bitcoin and other coins, because bitcoin has different characteristics, especially bitcoin will not disappoint its holder because one day it will give a very surprising price, but again it takes patience and quite high funds if you want to invest in bitcoin.
if you want to buy at $ 30K, your actions are also right, it's still cheap and it must be remembered that no matter what the price of bitcoin will be profitable, but the profit only depends on the value of the purchase.