Buying, the market falls; selling, the market rises. This happens because you must be making the following mistakes:
1 - Day trading. This is the best way to lose money. It has a direct psychological impact; sometimes you may have bet in the right direction, but the immediacy makes you think you will lose, so you end up making more losses than gains.
2 - You must be using money that you shouldn't. Using money that is meant to pay bills is a fatal mistake, as, like in the previous item, this will make the fear of losing interfere with your rational decisions, and you will most likely LOSE.
3 - Making leveraged trades. This may be the worst of the worst mistakes. You are not a fortune teller to know where the asset is going in the next 24 hours, so never do this; the market will run over you like a tractor. When greed speaks louder, you can literally lose everything.
What is the correct way to invest then?
Invest thinking in the coming semesters or more.
Always use money that you won't need in the coming years.
Study the asset before literally starting to invest.
Don't start selling as soon as you see the chart fall; calm down, it will come back. Depending on the asset, OK!
Know every detail and the context of the asset you intend to invest in.
In moments of market euphoria, do nothing.