Check it per capita though and we're in 27th behind Luxembourg, Norway, San Marino, Ireland, Netherlands, Austria, Sweden, Germany, Denmark, Iceland, Belgium, Finland and France from within the EU and a good 16 places behind your example of Saudi. We're down around the Italy, Spain, Cyprus, Portugal and Greece end of the GDP per capita range.
The UK is a sick country that killed off all it's remaining struggling industry and sold the population on a dream of all being middle classed, working in cozy warm offices and living in our privately owned dream homes whilst our kids all gained multiple degrees and all became global president. The infrastructure is underfunded and decaying to the point where it's little better than the likes of India (not surprising as theirs was last maintained under Queen Victoria too) whilst the industries that are needed to maintain and upgrade the infrastructure are in terminal decline with those who are qualified clearing off for better prospects elsewhere and us needing to recruit low cost European labour to make do and mend since our own labour force quite simply do not want to work outside for the rates the clients are willing to pay.
Don't let them kid you that the UK is a global superpower held back by Europe any more, we're a sad shambles who would lose any remaining semblance of global relevance if we were to exit the EU. As for all the migrants coming over here stealing our jobs, you are aware that there's as many Brits abroad in the EU as there are EU migrants in Britain aren't you?