I have seen a lot of people scalping and making it than those that does a full trading(hours, days) but they tend to lose so easily can we say it greediness or it's not advisable generally
The term greed is relative, you can't just conclude it for a whole trading system, and it depends on the person using the system and this is in relation to what the person does with the trading system as it is in other trading systems
Scalping is a trading system that is hyperactive on its own, this is because it requires the trader to catch regular market opportunities with a large risk in the shortest time possible. By virtue of this, successful scalpers will always make more money than regular traders.
The greed now depends on the trading plan of the trader. If such renege from the plan to earn more, then you can call it greed.