The most expensive line in your budget is an assumption nobody checked.

Every category runs on a shared belief about what its customer wants. It gets baked into the brief, the funnel, the product roadmap and the media plan — and then it stops being examined, because examining it would mean rebuilding everything downstream of it.

That belief is usually a decade old. It was probably true once. The competitor who checks it first doesn’t win by outspending you. They win because they’re answering a question you stopped asking.

Indian broking marketed the mechanism — the trade, the app, the brokerage rate — because the category agreed that investors wanted to trade. They don’t. What they want is the deposit, the school fees, the year they stop needing to work. Trading is only the machinery underneath.

Reframing a 37-year-old brokerage around the outcome rather than the instrument moved gross-sales market share from 1.6% to 4.3%, and SIP share from 1.5% to 3.2%. No new product. A different question.

The honest counter-case: some category assumptions are load-bearing. People really do want a cold drink to be cold. If you ‘disrupt’ a belief that is simply true, you get a clever campaign and a confused customer — and there are graveyards full of brands that mistook a real constraint for a lazy convention.

The skill isn’t doubting everything. It’s telling the difference between a convention and a fact. My test: ask who decided this, and when. If nobody can name a person or a year, it’s a convention.