The problem with the furlough scheme isn't really the money. It's expensive, but the cost of mass unemployment is greater.
The bigger problem is that we don't really know what the new economic status quo is going to be, and we are distorting the economy's ability to adapt for it the longer we sustain the jobs of the old economy.
Retail is a prime example. It is almost certain that a significant portion of retail spending that shifted online after lockdown, is NEVER coming back to bricks and mortar retail. That means the physical retail sector is now too large. Furlough actively impedes the process of efficient reallocation of economic resources from old (retail) to new (online sales and distribution).
Looking at the entertainment sector, whilst it's certainly the case that restaurants, bars and nightclubs will recover, it's almost also certainly true that SOME of these business will simply be non-viable in the new world, even post-COVID.
High unemployment is always bad, but the economy needs the price signals that tell it how to adapt to the new post-covid world. Without them, we're going to impede long term growth.
So we need a way of supporting people properly whilst letting unviable sections of certain industries die off.
I'd favour something like withdrawing furlough support for certain businesses, but vastly upping support for people made unemployed.