Should we wait 10 minutes to confirm a transaction I have read this proof of work calculation takes about 10 minutes. That mean people who are making the transaction should wait 10 minutes ? 

Let's imagine i want to buy a drink with bitcoin. The waiter should wait 10 minutes to be sure the transaction is okay before giving me a beer ?

Thanks
Yes, you need to wait, because the tx fee is too low, it won't be mined ever, so the transaction will be refused.

BUT if you're using the lightning network, you can create instant transactions. You can read more about lightning.

If you're dealing with tons of money, recommended to wait for 6+ block confirmation, because a strong miner can rebuild the last piece of the blockchain (this is almost impossible)