I always tell people that paying too much for a stock is the cardinal sin.
I don't normally trade stocks. I buy them and hold them 5, 10 or more years. The key to long-term stock ownership is owning QUALITY stocks at low prices. This approach has worked extremely well for me.
Stock PRICES fluctuate. Some do it more than others. But does the COMPANY'S VALUE change from day to day? I would argue that much of stock PRICE changes have nothing to do with VALUE changes. I've worked for a number of corporations and NOTHING changes very fast. It's like watching paint dry!
Take your home. Does the VALUE of it change every day? Maybe it does by small incremental amounts when you complete projects. If someone offered you 400K one day and the next day another person offers you 430K, did some magic VALUE fairy sprinkle 30K in gold dust on your abode to add 30K in VALUE? Well, it is the same for stocks.
Be smart, be well-read, be aware and be successful.
"Price is what you pay, value is what you get."
-Warren Buffett
“It's not what you buy, it's what you pay. And success in investing doesn't come from buying good things, but from buying things well. And if you don't know the difference, you're in the wrong business.”
-Howard Marks