Chelsea has gambled on their current crop of signings to be spectacular.
Leave the fees aside for a second. Players usually sign 4-5 year deals so they can negotiate bigger deals in 2-3 years. So to have players on 7-8 year deals the wages would be very high too.
Any player that doesn't work out is going to be a pain to get rid of.
Look at Sterling- City didn't want to renew on the wages he asked for. He was in the top 3 highest wages in the league when Ronaldo was there now he's top 2. Reportedly they want to get rid but he has 4 1/2 years left on a 300k+ deal. Good luck for them to get rid unless they give him on a free and subsidizing probably half his wages till he's 32.
In a world where Antony costs 100m and a Shakhtar player costs 100m, Paying 80 collective for Jesus and Zinchenko is a steal.