I don't know which model Daytona Clapton has. Some rare ones are very valuable. But it won't be worth anything like $1.6m. Paul Newman's 60's Daytona fetched $17.8m. Newman is not 10 times more famous than Clapton but his car racing exploits including at Daytona raised the value.
I cannot understand the recent fetish for owning generic kit that has been owned by famous people. There has always been such interest, but currently the price premium has multiplied enormously. Each Rolex Daytona of a particular model is the same as all the others.
Auction houses have latched onto this and now routinely sell the furnishings and personal possessions of the rich and famous either when they are down-sizing, need the money, or mostly their children cashing in after they pass away.
It is interesting stars can cash in on their fame, and make a lot of extra money merely for being famous. Possibly they should game this by owning a lot more stuff than they need, even more than they actually do.