In leagues with promotion and relegation, a club's revenue can change by a large multiple in a single season. That possibility drives almost every financial decision it makes.
The revenue gap is the mechanism
Top divisions sell broadcast rights collectively, and the money distributed to a top-flight club dwarfs what the division below receives.
Relegation therefore removes a substantial share of income at once, while the cost base — wages, staff, facilities — moves far more slowly.
That mismatch between falling revenue and sticky costs is what makes relegation dangerous rather than merely disappointing.
Contracts absorb some of the shock
Clubs write relegation clauses that cut wages automatically if the team goes down, and promotion clauses that raise them if it goes up.
These clauses make squads cheaper in the lower division, but they also make the club a less attractive employer, because a player is accepting a pay cut that depends on results he only partly controls.
Parachute payments serve a similar purpose from the league's side, tapering the income drop over a few seasons instead of applying it in one.
Survival spending is rational and dangerous
A club near the bottom faces a stark comparison: the cost of a signing in January against the value of another year in the division.
Measured that way, almost any transfer looks affordable, which is why struggling clubs spend at moments when caution seems obvious from outside.
The gamble works often enough to keep being made. When it fails, the club carries the wages into a division that cannot support them.
Promotion creates its own trap
A promoted club arrives with a squad built for a weaker league and one summer to close the gap.
Buying quality means long contracts at top-flight wages; not buying means a likely return downwards. Both routes carry risk, and clubs that alternate between divisions often carry the debt from previous attempts.
Why the system persists despite the strain
Open leagues keep late-season matches meaningful for clubs with no chance of a title, which sustains attendance and broadcast interest across the whole table.
They also allow a well-run club from outside the established group to climb, which closed systems structurally prevent.
The financial volatility is the price of that openness, and most regulation in European football is an attempt to reduce the volatility without removing the movement.