The difference between Bitcoin and other threatened systems (bank accounts, email) is that those systems can plan to go down for a day while they upgrade to a quantum resistant fix. Bitcoin can't go down for maintenance and implementing whatever solution is required is going to take time as it will require moving all UTXOs to new addresses. Given bitcoin's throughput of about 4000 transactions every 10 minutes, a solution must be in place months before any quantum threat becomes real. Plus, given that the proposed solution is a soft fork, wouldn't it be better to implement it sooner rather than later? Better to have it and not need it than not have it and need it.