You’re sticking to the standard defences, I see.
The Daily Mail is simply reporting on the outcomes of a Dutch academic study, using graphs taken directly from that study. It makes no difference which media organisation is reporting it.
If you’d rather have the data from the horse’s mouth, here you go:
https://docs.iza.org/dp17569.pdf
Secondly, re your point - ‘not all Brits are net contributors.’ I’m extremely surprised that you don’t seem to understand the concept of averages. Even including any British emigrants who aren’t net contributors, the average lifetime of a UK expat is still in the hundreds of thousands of euros. That means that many will be contributing far more than that, more than making up for the few who aren’t.
And the Dutch data shows that it doesn’t matter whether these people are asylum seekers - even if they come to the country legally, they are still, on average, net drains on the generous Dutch welfare state.
They are also disproportionately criminal, at a rate which - troublingly - increases in the second generation, as is clearly demonstrated by Danish data.