I guess depending on your purpose of buying bitcoin, if you are aiming to invest, then buy whenever I think is the right time, but if you aim to trade, then buy at the time the market is being dipped I think to be the right choice.

If the market is getting red then this will be the time time to buy or invest in bitcoin or other altcoin in marketplace, but if you do not have capital for investment then enter into the bitcoin bounty projects so that you will be rewarded with tokens and make it as an initial investment to bitcoin.

I imagine that in future our children and grandchildren will pay all transactions and goods and services with plastic cards or through electronic money transfers via mobile banking services on smartphones, which means paper money and coins will be extinct and not used again in the future.

Offcource depend on yours, depend on the your psycology and your trading strategy. As i know pro trader need acouple years to make consistent profit from trading, they hasbeen loss in many times, they become expert because alwasy learn from previous mistake. Trading will be worth it if you always patient , continue learn risk management and possible to manage emotions.