50% weekly for making profit on your funds is very big for me because it also depends on your funds how much you will deposit to trade. Its better to earn even small money than loss for it.
I wonder how much you have actually traded yourself. 50% gains are not common in everyday trading. This can be evident if you checked price charts on any site like coinmarketcap and did your own analysis instead of listening to what others say. Definitely a 30% or more gain is an imminent times to sell and book some profit because the crash or a correction would be coming pretty soon and you never want to be selling at the bottom of it, or miss out the opportunity.
However some people have different methods of trading and thats where differences in opinions arise.