RSUs are also much-less liquid and tightly controllable by companies than actual stock. That has made them attractive to management and insiders.
In any case, it is a bad idea to invest in the company you work for - unless you are high enough up in the company that you see the real books, or you have so much invested they have to show you as a large shareholder. (nobody is the later - large shareholders have a full time job managing their money not working for someone else). There have been a number of cases where a company has unexpectedly filed bankruptcy and someone lost their job and their savings on the same day.
I'd question this conventional wisdom, simply because you have a lot more information about the company as an employee than a random investor does, even if you are not in possession of things like financials that the SEC considers "material non-public information". Things like culture, intelligence of your coworkers, whether or not you're actually delivering on your commitments, how many feature requests and bug reports you get from your customers, mood of management, perks offered, etc. are all intangibles, but they are usually better predictors of long-term company performance than the financials that the company gives investors.
If your company is not doing well enough or is not something that you would consider investing in, you should find a different company to work for. Bad things are going to happen in your future, regardless of whether you own shares or not.
After about third earnings call (which happened a tiny bit before the trading window for our stock grants opened), I (re)learned the hard lesson that even if we delivered and I had actual, material, move the needle impact on corporate financials, that would not translate in any way to stock price. Except maybe if I pushed it really, really, down by causing an avalanche of problems that resulted in some big name deal going down.
The stock prices are vibe based, once its publicly traded your share value will be based on whatever vibes pushed numbers in excel around earnings call, and it's perfectly normal occurrence to beat expected earnings per share for 3 quarters straight and every quarter get a different vibed-off reason as to why the price should go down.
Amazon for instance has over 1 million employees. You know nothing about most of your coworkers or whether other teams are delivering featured
Every time I got an RSU I could just sign into my RSU account and press a single button which sold them all, put a portion of the proceeds aside for taxes, and deposited the rest as cash directly into my bank account within 1-2 business days.
How are options more liquid than that?
