What's your advice to someone new in this space?

Put 100% of your net worth into BTC, and just hold. https://twitter.com/AWice/status/1326997059254112256

What's your advice to someone who wants to start being a trader?

Don't. You'll lose it all 99.9% of the time.

If you really badly want to trade risk for gains, then (after buying spot 100%) buy long dated futures on very low leverage.

Why should I invest in BTC, I can't get enough gains? Please recommend an alt.

BTC is one of the best investments in the crypto space because the risk is the lowest. When you buy a shitcoin, you can lose it all. Most likely you are buying a shitcoin based on the recommendation of someone else who may not be able to tell opportunities from scams.