Let’s say the company you work for goes public and your stock is suddenly worth $1,000,000 (as an example). A wise investor, you normally put all of your other savings into broad market index funds. Now, do you sell your company’s stock that was given to you and took you four years to vest into, or do you hold on to it and hope the valuation keeps rising? (This is a rhetorical question btw)
EDIT: not all wealth managers are scam artists. If you suddenly earn lots of money and don't know what to do with it, find a professional paid by the hour to advise you. Do not listen to the people telling you that anyone charging you for advice is automatically a scammer. Also don't listen to people telling you that it's "not that hard" without any context on your experience and understanding of finance. They have nothing to lose by looking smart and confident on the internet while discussing your money.
It depends on your overall net worth. If the stock represents the majority of your net worth, you might want to diversify across different types of assets - your newly introduced tech stock being on the high-risk end of that spectrum. If on the other hand you have "enough" of your savings in lower-risk assets, then it can make sense to keep all your stock.