What’s the alternative?
Let him leave next year for free, which would be a £50m asset walking out the door for a big fat £0, for everyone to throw their toys out of the prame like they did with Herrera, then spend £50/60/70m on a replacement?
£350k a week might be a lot of money, but it’s cheaper than losing him on a free and having to spend big money (using Ederson, Kepa and Alison as ballpark figurers) on a replacement.
De Gea on £350k for 5 years is £91m.
Buying a replacement for say £60m and paying him £150k for 5 years is £99m.