My husband wants to invest his entire paycheck in the stock market!

So we both earn a combined 30k/m, this is an additional income, and our fixed expenses are covered. Our savings for emergency fund is already done.<br><br>Now my husband asked me whether he should invest his entire paycheck in the stock market, and if he should open a robo account or ask his broker to handle his portfolio. I personally think it's a bad idea to put all his money there.<br><br>What do you think about this idea? Are there any risks?<br><br>I'm so confused what to suggest to him. I already told him that diversifying the money is a better idea and investing it in other places too.<br><br>He doesn't want to invest in other places because he believes investing in the stock market is the best way to grow his money, he also explained that he wants to invest in a long term so it doesn't matter if the market is unstable right now.<br><br>But isn't there a risk that if he invests all of his money in the stock market and the market will crash, then we would lose everything!<br><br>Plus he wants to use a robo account for his investments, so it's all automatic and he would save time and energy, but I told him that it's always better to have a financial advisor or broker handle it, I don't fully trust robo account, I feel like it's a gamble.<br><br>In summary, what would you do in this situation? Should we diversify the money and invest in different places or is it okay to invest everything in the stock market?