£25 on a 50k holding. So disappointed
Don't be. The odds of each bond winning is about 1 in 35000, which means that you should win, on average, 1 or 2 prizes each month, and about 98% of prizes are for £25.
You have to look at it over the long term and with that holding, you should expect about 17/18 x £25 prizes a year, with perhaps a bigger prize every 5-10 years. But if you take hundreds of people with £50k holdings, it will vary more than that with most winning between 15 and 20 per year.
If you have £50k in bonds, they can't all be in £25 blocks unless you've spent decades buying £25 a time.
A £45k bond value means that someone bought £45k in one go. A £50k holding means that person has a total of £50k in premium bonds.
You should look at them as gambling the interest you would receive from instant access savings.
The best rate currently is around 0.6% or up to about 1% if you get a notice account of a year or two. So with these accounts, you'll definitely get £300-500 per year in interest. Put the same in PBs and you might get more or you might get less, but getting substantially less is probably quite unlikely. But if you don't want to take the risk, maybe they aren't for you.