//I would imagine Miller as well as Swintons hubby had investments/companies tied in the EU hence the reason for their hysterical rants about stopping Brexit.//
Here's an article about Alan and Gina Miller, written in 2012, long before Brexit was a twinkle in Nigel Farage's eye. You can make up your own mind whether their finances might fare with the UK in or out of the EU:
https://www.telegraph.co.uk/finance/newsbysector/banksandfinance/9178005/Alan-and-Gina-Miller-the-husband-and-wife-team-shaking-up-the-investment-industry.html
Mr Swinson (aka Duncan Hames) is a strange fish. He trained as an accountant before becoming a local councillor. In 2010 he was elected as a Lib Dem MP and was PPS to Nick Clegg. Since being chucked out in the 2015 election he has risen to become acting Executive Director of something called "Transparency International". That is an organisation which devotes itself to seeking out and addressing global corruption. I imagine, therefore, the EU is of interest to him from that viewpoint. But it may be that, according to its accounts on its own website, in 2018 Transparency International received £3,463,555 from the European Commission.