Better Understanding Your Employee Stock Options
medium.com
medium.com
In addition, you may owe tax at the time you exercise the options if your strike price is below the fair market value at the time of exercise (also depends on the type of options, there are two).
Also, you say that employees can't exercise options until they have vested. The truth is that you can early exercise if that's written into the stock plan. It makes things a tiny bit more complicated for the employer, but can provide a huge advantage to you. Many startup founders down't know about this, but will add it if you ask. Effectively you can buy all of your shares immediately, starting the capital gains clock ticking and eliminating any tax liability at purchase. If you leave, the company has the right to repurchase any unvested shares. The only downside is that you need to come up with some cash upfront.
Given the nature of 99.9% of employer/employee relations, especially in salary negotiation, I would never personally place any value in stock options of any sort. There is simply no verifiable way to calculate what they are worth with a million different ways for them to become worthless and no accountability for a company to be entirely forthcoming.
1) A lot of people do make money off of employee stock, you just have to be reasonably intelligent about it. This blog post is a good way to model risk/reward.
2) Thinking of your employer as your enemy is a great way to set yourself up for failure.
3) Don't think of stock as worthless, think of it as a bunch of lottery tickets. It has some probability of being worth something based on the lottery.
I'm not suggesting you consider your employer an enemy, there's obvious a mutual benefit to you working there, but never should anyone assume a business has your best interests at heart because they almost never do.