I'm somewhat new to this topic (and therefore might not understand correctly) but another user, 'oillio', made a response in a different thread [0] which could explain 'getting diluted away to nothing', for example, an investor invests money causing dilution, the company squanders the money or uses it on something that doesn't positively affect the company trajectory. You now own a smaller slice of a pie which is the same size as it was before.
Using his example, if you estimate the value of a company to be 100M and estimate 10 years until IPO, if the investment doesn't raise the value of the company at the time of the IPO in 10 years then the dilution is not good for the employee because the pie is the same size (100M) but his/her shares have been diluted.
Seems like it's pretty difficult to estimate the value of the company in 10 years or the IPO date though which is probably why people just use the amount invested to estimate the value of the company.
Using his example, if you estimate the value of a company to be 100M and estimate 10 years until IPO, if the investment doesn't raise the value of the company at the time of the IPO in 10 years then the dilution is not good for the employee because the pie is the same size (100M) but his/her shares have been diluted.
Seems like it's pretty difficult to estimate the value of the company in 10 years or the IPO date though which is probably why people just use the amount invested to estimate the value of the company.
[0] https://news.ycombinator.com/item?id=14510483