Football is the world's most beautiful game and it's a lucrative sport for obvious reasons. European football is followed by fans all across the globe and there is never a shortage for sources of income as far as top football clubs and players are concerned.To remain at the top, clubs have to furnish or reinvest funds in order to secure the best available personnel that could buoy them towards greater success. Some of the best performing teams in the 21st century are those that have been prepared to break the bank in order to improve their side.On that note, let's take a look at the 10 clubs with the highest transfer spending since 2000.#10 Atletico Madrid - €1.35 billionJoao FelixAtletico Madrid have become or have been forced to become big spenders in a bid to upset the Real Madrid-Barcelona duopoly in the La Liga. After breaking their transfer record in the summer of 2018 to sign Thomas Lemar from AS Monaco, they paid almost double that amount in order to secure the services of Joao Felix.Felix was bought for a sum of £113.40 million. But they have conducted their business rather responsibly and have bought players who have helped transform the side like Antoine Griezmann, Radamel Falcao, Diego Costa and Rodri to name a few.#9 Liverpool - €1.48 billionLiverpool players celebrate their UEFA Champions League triumph in the 2018/19 seasonLiverpool tasted Premier League glory for the first time in the Premier League era and that is, in no short measure, thanks to the wise investments they have made towards improving their squad.Liverpool's transfer business in recent years have been spot on. Klopp has been able to identify the right players to bolster his side and the board has backed him by spending heavy in the transfer market.They have bought the likes of Virgil Van Dijk, Alisson, Naby Keita, Fabinho, Mohamed Salah, Roberto Firmino and Sadio Mane over the course of the last five years and though these players have cost a fortune, they have helped the Reds become a juggernaut of sorts.Salahs first 50 goals for Liverpool 🇪🇬One of the best signings in the club’s history 👏 pic.twitter.com/OazWDnPNSh— View of the Kop (@ViewOfTheKop_) September 11, 2020#8 Paris Saint-Germain - €1.55 billionNeymar and Mbappe have cost PSG a fortuneParis Saint-Germain were catapulted back into relevance when Qatar Sports Investment took over the club in 2011. They started spending heavily almost immediately and signed the likes of Zlatan Ibrahimovic and Thiago Silva for a combined £56.7 million.For a club that has only spent massively in the second decade of the 21st century, Paris Saint-Germain have made this list thanks to two of their most expensive acquisitions Neymar and Mbappe.They initially bought Neymar from Barcelona for £199.4 million and followed it up next summer by making Mbappe's loan move from AS Monaco permanent for £130.5 million.They have also spent heavily on players like Angel Di Maria (£56.7 million), Edinson Cavani (£58.05 million), Mauro Icardi (£45 million) and David Luiz (£44.55 million) to name a few.Neymar and Mbappe cost Paris Saint Germain £330 million but failed to score in the Champions League Final. Bayern Munich starting XI cost £90 million. #ChampionsLeagueFinal— Alan Travis (@alantravis40) August 23, 2020