From a personal level, it allowed me to keep my job. The UK team was disbanded and moved to Germany just over 10 years ago, such easy access to work in Germany was a massive boost and gsve me the opportunity to sample a different culture without any visa and other paperwork hassle. Luckily, when Brexit hit, Germany understood the importance of being human and made the process of getting residency extremely easy.
Married over there, to a US/German, wanted to come back closer to family but unfortunately spousal Visas were ridiculously difficult and could have had us separated for up to 6 months before my wife's case was even seen to. We moved to Ireland, which still as an easy access to work fir UK citizens, extremely cheaper university programs for my wife, as an EU citizen. The course she is doing is 4 times more expensive for non UK citizens than in Ireland, for EU citizens.
The EU invested heavily in a lot of UK projects and many in Liverpool & Merseyside. There were reports straight away how much money some regions and cities were now going to lose because EU funding would stop.
Politics aside, being part of EU funding programs was massive for the UK.
I remember reading a few times (sorry, no link) that the UK was actually getting more money from the EU than we were paying in. May be wrong but it is something that rings a bell.