Well, I don't know how much this is important to you, but if I were you I would go straight to customer support to inquire why people are receiving the $250 bonus and you are excluded from it. Perhaps, you will automatically receive it when complete the KYC, but I am not sure about that, which is why you should still ask.
Another possibility is that it might be distributed based on your activities on the platform. If the system deems you as so inactive, Stake may not be compelled to include you.
Not all accounts get a bonus offer to complete the KYC and not all accounts get $250 they have criteria such as game activities and VIP level, if your account level is bronze then the bonus is between $10- $50 yeah depending on your deposit/game activity or even you don't get any bonus offer but if your VIP level platinum1-4 the bonus is between $100-$250 and generally for this VIP level all will get a bonus offer. I think those who don't get a bonus offer will ignore the KYC because they can create an account anytime.
I personally have not got a bonus offer related to KYC because my account has been verified since last year but of course I got another bonus from my birthday, there are also those who get bonuses based on when the account is created.