Re: investment in bitcoin should be short term or long term.
Short-term investment can be considered gambling or lottery. You can lose (most probably) or you can win (if you're lucky). If it's time-limited and you need to cash out at some certain time it's always a bad idea. There's a significant chance you'll have to liquidate at a loss. 
Investment isn't a kind of gambling/lottery. But if you invest in shit coins or meme coins, I agree that it can be said to be gambling. So, gambling or not, it doesn't depend on how long you invest, it depends on what coins you invest in. People who invest in coins with good fundamentals must be based on deep research and analysis. They also use certain strategies to optimize profits. While gambling, mostly depends on luck. Research, analysis, or strategy may have no significant influence. So, basically, investment has a bit different approach.Whether you invest in bitcoin or potential coins would be called gambling if you have no knowledge of it. The only difference between investing and gambling is knowledge, knowledge is what will help you differentiate what you are doing with your money. Investing requires knowledge, but no matter how good your knowledge is, if you don't get lucky, you will always lose.