The study says this one, traders are losing because they lose opportunities in the coming years and I have to agree on this one since I do trade BTC before and I regret doing that because of the value today. Anyway, we all have different strategy and we cannot blame traders for actively working on the market so they can achieve their goals. I personally play long in stock market and do trading in cryptomarket, its about your risk tolerance and of course your availability.
Good strategy though, the stock market is more secured as it's less manipulated compared to the crypto market, but in terms of profitability, we can make a bigger profit in crypto if we are smart enough in finding the right opportunity. The high volatile market could give better profit for smart traders, that's why we can't blame some people who focus on crypto as there's big money in here.
Stock market is as easily manipulated as crypto, even more so in that regard. The only difference is in the stock market world there is SEC which would stop you if you do not bribe the politicians first, in the stock market world you could literally bribe a politician, get a new law passed, and after you make a deal with the politician about it, do a huge buyback of your stocks, then get the deal officially put into law, then sell after the stock increases and you made a huge profit. This has happened a billion times already, it is perfectly lawful as well.
Crypto is decentralized, it can't be manipulated that way because there is nobody at the top making decisions, however it is also manipulated because with one Elon tweet it can go up or down, but it is still all the people who buy and sell that make the decision. For example, SNL sketch of Elon was seen as something that would increase the price, it plummeted it.