Every option is partly made of time, and time melts. Theta is the rate of that melt — how much value an option loses each day if nothing else changes. Buyers pay it; sellers collect it. The entire premium-selling business, the wheel included, is a bet that theta decay is the most reliable force in markets. Most days, it is.
Why decay accelerates near expiration
An option with 60 days left loses value slowly — there's still plenty of time for the stock to move. The same option with 10 days left bleeds fast, because every passing day removes a meaningful slice of remaining possibility. Decay follows a curve, not a line, and it steepens hard in the final weeks. That curve is why so many sellers open trades 30–45 days out and close them early: you ride the steep part without holding through the most reactive, gamma-heavy final days.
Theta is rent, and the stock is the property
A useful mental model: selling a cash-secured put is renting out your willingness to buy the stock. Theta is the daily rent payment. The strike distance is your security deposit terms. Rent is collected every calendar day, weekends included — which is also why premium on Friday afternoon already reflects the weekend's decay. Nobody is giving away free Saturdays.
When theta isn't enough
Decay is reliable; it is not unconditional. A short put losing to a falling stock is losing delta dollars faster than it's collecting theta pennies. The sellers who get hurt are the ones who watched the decay and ignored the direction. Theta pays you for time and risk — when the risk shows up, the time income doesn't cancel it.
Track your decay capture, not your fills
The practical question is what fraction of each premium you actually keep — your capture rate. Sellers who consistently close around 50–70% of max profit usually out-earn those who hold to expiration, because they redeploy capital onto a fresh, steep decay curve instead of babysitting the flat end of an old one. You'll only see that pattern if every open and close is tracked against the clock — which is precisely the kind of math that should be automatic.