It depends on how much you are trying to make a month. Can you make at least $10,000 net profit a month with $100,000 cash --in my opinion yes --especially in daytrading S&P 500 futures and closing out all positions before the end of each session.
But for alot of people $10,000 per month is not making a living and they want to make $500K per year. Although there are some people that are that good at trading that if they only have $100K to trade with (and never add to bases capital--always stays at $100K) that they can make that kind of money--$40k a month (or more) on only $100K capital is not realistic
Can you make $10,000 per month trading stocks with $100k and say having $400k buying power intraday under PDT rule and closing out all positions before the end of each session?
Again I would say that is certainly possible even trading large cap like AAPL and averaging $500 per trading session net profit - 20 sessions a month.
You have to:
1) Spend at least 5,000 hours to 10,000 hours practicing and developing a consistent trading edge that works regardless of daily market conditions
2) Create a trade plan & risk mgt plan before each session
3) Write down a daily trading report journal of what you did right & wrong
4) Continuously learn from mistakes and take consistent action to correct mistakes
5) Be willing to be completely objective and honest with yourself whether you are correcting past mistakes or just very suceptible falling into old bad habits. You also have to be willing to be honest with yourself as to whether you have what it takes to be consistent and successful in the trading for a living business (or whether you are just lucky every now and then and really have no edge, no risk mgt and no real daily plan that is consistently profitable regardless of market conditions)
Can you make alot more money selling educational courses, trading software, trading chat room trading subscriptions, trading daily picks services and newsletters--
I would say that technically yes --its probably easier to make more money that way but you still have to have some sort of credibility (unless you want to be one of these fake trading gurus on stocktwits or twitter ( SEE:
https://twitter.com/guruleaks1?lang=en ) that just trade 2 different fake TD ameritrade thinkorswim accounts every day (1 fake money trading acct for big money long plays and 1 fake money trading acct for big money short plays) and then just post the massive "fake" winning trade(s) each day (whichever one it turns out to be--the long play or the short play of the volatile stock of the day) along with pictures of you with beautiful women , piles of cash , rental private jets and rental lambos- and your ok with being a fake trading fraudster