That imagined world,
in which individuals only wanted to invest their money in stocks and not on any other product that has anything less than X% annually
is inconsistent with how people think about investments (and how financial markets work).
The reason is that returns are not static, but respond to demand. If everyone wants to just buy stocks with certain expected returns, it will drive up prices of stocks. This will go on until the expected return falls below the returns of the safe assets (although, in hindsight, these expectation may turn out wrong). The expected return falls with higher prices, because the discounted underlying payouts from the stock stays the same (unless something else changes, for example the economic outlook, or the money supply). Note also that as more and more people selling government bonds, their price falls and returns increase. So, other things equal, there will be a price level of stocks above which safe assets become more profitable. At that point people will stop buying stocks and invest in the more conservative option. What I describe above is a narrative (how things would move if they weren't where they are already), but usually these things happen all at the same time.
So a world as you suggest is difficult to imagine, because x% is not fixed, and people will not always want to buy a certain asset.
Of course, people may expect stock prices to continue to increase beyond their fundamental value, justifying continued higher expected returns (when including the sale of the stocks at some later point). This can go on for a while but ultimately results in a downward correction of stocks prices (a soft landing or a crash).
Note also that the choice of investment heavily depends on how much people like or dislike the risk associated with the investment (risk aversion). Some people attach so much worth to a safe investment that they will still invest in government bonds, even if stocks have much higher expected returns. However, in most cases, people prefer to hold a mix of risky and safe assets.
Key words here are: