This is especially true during low volume and fast moving markets.
Ahh ok, I take your point. I thought we were talking only about the BTC/USD market on Coinbase Pro, as that is the trade that OP wanted to make. Unless you are trading very large amounts on that market, then the amount that your market order will move the price is pretty insignificant. Looking right now with the price at $56,000, there are around $700,000 of sell orders before you reach $56,100, and you would need to buy over $3.5 million in bitcoin in one go for your final price to end 0.5% away from your starting price. If you want to buy now (i.e. not wait for multiple ladder orders to fill, not pay attention to trading indicators, etc.), then for the vast majority of people buying up to ten thousand dollars of bitcoin at once, the difference between a market order and a limit order will be negligible. As OP is just looking to buy and hold and not actively trade (as he was going to do on Coinbase rather than Coinbase Pro), then the easiest way for him to save a significant amount in fees (~$150 or so), is to simply place a market order for $10,000. He will still end up far better off than if he had bought on plain old Coinbase.
I take your point that if you are using very volatile markets with poor volumes, or if you are more interested in reading charts to find the optimal buy in point, then limit orders are the better option.
