Investing in the stock market, is generally betting in a situation where there is a net win. That is, most of the time, even bad investments don't lose money in the long run, they just don't win as much as you could have one, or they have greater fluctuations than a portfolio with an equivalent return.
Day trading is however very addictivive. even people who only trade weekly will still check their stocks many times a day. As the problem goes on, penny stocks become a big lure as they have higher fluctuations giving one chances to Win big (a great feeling compared to inexorable index funds slow creep).
So does one have to be a masochist to be addicted to gambling? apparently not.
Even index funds are somewhat crazy. Right now the SP 500 trades at high price to earnings multiples even in stocks are unlikely to achieve earnings that can match that price. It's a combination of the greater fool theory along with the unusual condition that there's few "safe" places to put money right now. There's too few shares of stock in health companies (due to the slow economic growth) being chased by too many dollars. As long as the chase continues then it's "safe". But long term enormous growth is required to match those P/E multiples. Google and Amazon have essentially no earnings.