So don't do that. Always carry some cash and your debit and/or credit cards. Spread out the risk (especially when travelling).
> you lose access to your email/bank/github/etc. accounts protected by 2FA so you may not be able to work;
So don't do that. If you enable 2FA, have backups and recovery codes. Assume the phone will get lost at some point.
> you may lose your airline/train tickets (unless you have a physical copy with you) so you may not be able to travel.
So don't do that. When travelling I always take the printouts of the tickets along, even if I end up not needing them.
Don't turn your smartphone into your everything. Treat it as a tool which can get lost, stolen, or broken.