This is true except there are often sides in a debate that lack credibility.
Tim Palmer suggested the benefits of Brexit were shown by there being more investment coming into Britain than leaving Britain.
I do not see this as true.
The net inward and outward foreign direct investment is a poor measure of a country's economic position.
Post-referendum inward FDI has indeed been boosted while outward FDI declined, even turning negative in 2019.
However FDI is a measure of UK businesses being bought and sold by foreigners and foreign businesses by Brits.
It measures mainly the change in ownership.
More useful for judging an economy is the level of business investment.