IMO, and with no more facts than you have shared (which is fine, of course), I'd try to get my options treated analogously to how the investors' shares are being treated. (IOW, can you sell your shares at the same terms [adjusted appropriately for "round"] as the investors? If so, is that profitable after paying the exercise price? If so, do that.)
Most of the value of most businesses is in the terminal enterprise value, not in the stream of "future, maybe someday" dividends. Absent an IPO, you may have a very tough time every extracting this value.
Now, if you have 100K shares at an exercise price of a penny and $1000 won't change your life, I'd definitely exercise and hold rather than letting them lapse if the founders won't buy you out.