No, it's not...
Look at the Carnival event & the two 'random chance' florens games,
which are the same mechanics as when cashing in for a prize chest
If you doubled the 15% odds to 30%, you needed 11-12 tickets to 'guarantee' victory.
If you doubled the 5% odds to 10%, then you needed 42-44 tickets to 'guarantee' victory.
Of course, there's still always the roughly 1% odds you spend the required total amount and get nothing, but hey, that's random variance for you!
More attempts at the same time is needed to account for the random variance & reduce the odds of failure.
Yes, Inno is using some awful RNG generators, but still, probability is probability and the only difference is whether the variance is going to be 1% or 3% or whatever who get 'RNG-screwed'.