Read the books Market Wizards and the story about the Turtles. In that period very simple strategies worked without any problem. There was no internet, so the only information that was available was there fast for the professionals and days or weeks later only for individual traders. People who wanted to trade forex received quotes that were even 20 pips away from the market price. So they could never compete against the professionals. Friends called me, as I was the only one with realtime quotes, to check the quotes they received from their brokers. They were robbed even before they sarted to trade.
I rented a Teletrac in the early 90's for 1,850$ + 21% taxes a month. Datafeeds from Esignal were 185$ + 21% taxes a month. Except from the professionals nobody could afford that. In my country I was the only private client from Dow Jones Telerate at that time.
Nowadays programs are almost for free, internet is very cheap and gives the same information at the same time to small traders. Opening an account is much easier, and minimum account size is much smaller. Etc...
I was already daytrading before you could read or write.