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.
Maybe they are expecting to much that everyone will do that thing would make them eligible to $250 bonus. But some of them got disappointed because they didn't get something. Maybe before considering those thing and for them not to expect anything better if they verify these information they read so that they would not get disappointed if they became not eligible for the bonus offered for some people which meet the requirements or certain levels in their casino.
Maybe they should clarify this to their support to get proper inputs and they will not speculate or say something crazy opinions related to this matter.