3 things (perhaps a different angle than you would expect, but they are still relevant and true):
- Although there might had been one or two start-up home runs born in Sweden (Klarna is another), these are rather the exceptions and not the norm. It does not really reflect the overall picture. The grand total of GDP revenues generated from the tech industry is in fact a lot larger in the UK (due to the different in size of these countries, you are right there; might be interesting to compare per capita instead to get a more accurate comparison). In the UK, Revolut, Checkout.com and Monzo come to mind, but again, these are only the top tier of the market and does not include the combined other 80% of the market, or whatever it is.
- Let's not forget about the elephant in the room, Brexit. Amount of investment into the tech sector depends on how much government revenue there is. This is a function of GDP, and since Brexit, GB has literally become the weakest economy in the G7. It's not 2013 anymore. It was shown that the size of the UK's economy was around 90% that of Germany's prior to Brexit. After Brexit? 20% smaller, so 70%. That's material change. Guess the impact of this on tech spending, not great: the lower the GDP, the less there is to put into growth sectors and tech is only one component of the economy. See this week's Budget, where a significant amount was committed to tech hubs around the UK, which is definitely a step in the right direction as the strength of this sector can be built and capitalised upon and expanded even further.
- Lost access to large talent pool, again due to Brexit. Except for a few PhDs and other heavy-hitters who might go to the UK for research etc, where do you think the average adventurous European software developer will go to work post-Brexit? Xenophobic London, with the added hassle of sorting out a work visa? Perhaps not. They'll go to Stockholm and work at Spotify, or Klarna, Paris, Berlin or Frankfurt. I'm exaggerating a bit here, but you get the idea. It's real.