[meric]

One set of preparation can be good for more than one opportunity. E.g. Saving up $100k, which can be used for the following opportunities: Housing crisis, stock crash, initial investment in a startup, travel. It can also be used for the following unfavourable circumstances: sickness, accident, personal reason for travelling. A more narrow form of preparation could be learning a skill, e.g. programming, which sets you up for possible startup ventures as well as a full-time job.

He's not saying that you shouldn't try to seize opportunities when you may not be fully prepared; He's saying when opportunities are available, you will be more able to seize it if you're more prepared.