LOL, Upwind.
You claim tax credits because you need them to survive, not to top up your savings.
You claim them, and get DOZENS - literally - of award notices, all with amounts varying by just a few pounds, so you don't really know what your true entitlement should be.
Then, 3 or 4 years later, you get a demand notice for thousands of pounds you're supposed to have lying around, saved up from your min. wage job.
THAT is what happens, not big payouts you set in a bank.