> Any plan will certainly be wrong, so there no point wasting time making one.

There's a famous Eisenhower quote that goes something like, "Plans are useless, but planning is indispensable."

The point being that any single plan is likely not to pan out because of unknowns and surprises, but by going through the process of planning, you have "cached" knowledge about your domain like what the opportunities and threats are and you can use that knowledge to adapt when the specific plan falls through.