Ah, I'm sorry, the frequent rejection inherent in academia is one of the suckiest parts of the job! Any why I now work in uni prof services rather than in research!
You're allowed to be upset and frustrated about this - but try and limit wallowing to a day or two before pulling your socks up and thinking about next steps. Try to remember that pretty much the maximum success rate for funders is 25%, and most are much lower, at 5-15% - so it isn't a 'failure' on your part that four out of four bids have been unsuccessful, it's just part of a numbers game weighted against you.
All my sympathy if that's what you're looking for - if you want advice as well though, a whole bunch of questions below:
Can you repurpose this grant for another funder?
Have you been submitting the same research idea to all four attempts or different projects?
Have you been getting feedback from the funder? If UKRI, what scores have you been getting?
Are these big or small applications? What career stage are you, and do you have a track record of securing funding?
What is your publication track record like?
Are you getting your grants peer reviewed before submission?