I noticed this practice years ago.
Amazon is like the stock market.
The availability of an item and its demand determines the price on an hourly basis.
Years ago I was looking to buy a 55" LG TV.
The price fluctuated $100 from am to pm.
From one day to another.
I finally caught the lower price and closed the sale.
A week later, it dropped still another $120.
Fortunately, Amazon refunded the price difference after contacting them.
But as I understand it, they will do that only once on the item.
If it drops another $100 a day later, no difference refunded.
Just think of it as the stock market. Jump in when you think you have the best price, and consider how badly you want the item.