How to think about an options tender offer?

In my previous job I got stock options, even though the company was still private. When I left the job, I paid the company ~$12k to buy these "unborn" stocks (excerzise the options?).

Now the old employer made me a tender offer. I can sell back my options for ~$70k. This sounds like a great gain and good deal, but I am wondering why the company offers this. Maybe they are about to go public and assume their stock will be worth (much?) more than what they offer me now?

When a competitor went public a few years ago, their stock went up, and later that competitor got bought by another company for a lot of money.

I don’t need the money right now; this was always meant as along-term investment.

What do you make of this offer? What should I be thinking about?