Maizie because the scientists, technologists, world class university departments and research centres are in the UK and as well as producing highly qualified British scientists, they are so good the best scientists and technologist from other countries want to come here to study and do research,
The easiest way to make use of their work and have the scientists close by to advise and undertake commissioned work, is to set up your business where all these people are.
It is much easier for an entrepreneur to set up a business where there is a large number of highly qualified people, than to go to all the expense of trying to set up a minihub in another country.
While many people do go and study and work abroad, it is often only for a few years and it is to other centres of excellence in their discipline; big North American or European universities and research centres.
Most people prefer to stay in the countries they were born and brought up in and where friends and family are. They are not going to move away from world class institutions, with so many fellow scientists round them to go to some small minihub thousands of miles away, which cannot compete with where they are, and could fail and leave them marooned and without help in another country.