10 · Cost

The real cost of holding the roof up by hand.

Your acquisition cost didn't jump. It crept. A few percent here, a platform change there. Creep is worse than a jump, because nobody calls a meeting about creep.

01 · Worked example

The maths, on a worked example.

The numbers below are illustrative. Swap in your own. You can tell your blended CAC to the pound, so this will take you two minutes.

Say you spend £15,000 a month on paid, and your blended CAC has risen 30% over 18 months. That's the range we see most often in businesses at £50k to £250k a month.

Row
Line item
Figure
01
Current paid spend / month
£0
02
CAC rise, trailing 18 months
0%
03
Customers now bought by the same £15,000
≈ 25% fewer
04
Spend required to hold customer volume flat
£0
05
New spend, annualised, just to stand still
£0

And if the creep continues at the same rate, you run this exercise again in 18 months from a higher base.

02 · One-way

The auction gets more crowded. Your house doesn't get more walls.

More advertisers bidding on the same eyeballs. Privacy changes degrading targeting, so the machine needs more budget to find the same buyer. Platforms whose revenue target is your ad spend. None of that is a scandal. It's just the direction of travel for rented attention.

The part you control is what's underneath. A roof with load-bearing walls under it costs less to hold up every month. A roof with nothing under it costs more. That's the whole argument.

03 · Not anti-paid

The roof stays. Let's be clear about that.

05 · Book

Find out how much weight you could take off the roof.