In order to day trade in US stock exchanges you need to have a minimum of $25,000 in your account plus some more to give you buying power to trade with if you want to make more than 4 trades a week. If you have zero commissions then you can trade pretty small trades to start out but you still need the 25K to start.
In contrast you upload $50 to a
poker site and start playing the micros and work up from there.
So if you have the money to day trade you can give it a try, but you'll be taking more risk. And most people who give day trading a shot will lose money just like most people lost money playing poker. You will need to take the time and study how to trade and its strongly recommended you practise in a simulator first before attempting real trades.
If you get good at it and have the skills it will be more money for less of a grind than poker. But won't come without significant work and risk to learn what you are doing.