Well, from the user who shared his bonus offer from stake.com I don't think he said anything about him being inactive which may have attracted such jaw dropping bonus to him. So it's just a random actually. But in all, it's better to stay active enjoying the games in Stake platform while hoping you could be the next in line. Because you can still stay inactive and get nothing since it's something that seems to be random.
Gambling platforms don't usually give users who are inactive bonus, they only do that to those who are active using their platform, though they do something that when they noticed inactivity on a user's account after gambling for a while, they present bonus base on their previous activities and wager made and encouraged them to be active and continue with gamble again on their platform.
And thats how gambling business works on which they would be trying out to get in touched with those who do become inactive. They would be trying out to make those gamblers do go back to play.
We dont know if they would be that trying to make up those invites or giving out some bonus including into those who are just that small time gamblers if ever they would be that also getting up the bonus.
If there would be no exemption to this then they would be that including it but the bonus amount might be that basing up on how much you had wagered or vip level account?
It could also be referred to as keeping in touch with a customer even though it's all about business. Perhaps it could be that the gambler who left his account inactive may have gotten or be getting better bonus offers once in a while from some X gambling platform and had to abandon Y platform which has for long not encouraged the gambler with any, no matter how little the amount. So having to receive such unexpected bonus can likely propel the gambler to revisit the account and see what luck lies ahead for him in there.