Actually there's nothing wrong at buying whenever you have the money available but I think what he/she meant by timing the market is just by buying at each dip that occurs, take for instance a week+ ago bitcoin price moved up to $47,000+ and after a while dropped to $39,000 then later took a leap to around $43/42,000+ right now (as at the time am writing this). For a investor that is timing the market he/she will know that $39k is a right time to buy because the price will surely move up again for him to make profit and for sure it did moved from $39k to $43k, so isn't it a right timer for any investor? We know the market is unpredictable but there are moves that we will critically observe and we won't need a fortuneteller to tell us what could happen next, only experience will tell.
Buy now because it is no longer at $43K but is trading at $42.5K. When the price rises to $45K, then the profit has been made.
Buying whenever you have the money to buy can be done, but strategic calculations for making a profit will not be ignored for those who use Bitcoin as an investment asset.
I think when someone tells you to try using the DCA method in purchasing, then that's good advice to increase your Bitcoin holdings.
Buying Bitcoin at whatever price and whenever it is done will not result in a loss if the aim is to hedge against fiat currency, but if you focus on buying Bitcoin to expect profits when the price is high, consideration of using methods and strategies in buying is important.