Theta is the erosion of an option’s value as expiry approaches. The general mechanic is the same everywhere and is covered in theta decay. What differs in crypto is the calendar it runs against.
The weekend, and what crypto does not have
In equities, time passes over a weekend but the market does not trade. Two days of decay come out of the option while price cannot move. That produces a genuine, well-known asymmetry — and a set of strategies built on selling premium into the weekend to collect decay against a market that cannot move against you.
Crypto trades continuously. There is no gap between calendar time and trading time, no weekend decay to harvest, and no Monday gap to fear. Decay and opportunity for the price to move accumulate together, always.
That is genuinely simpler. It also means a strategy imported from equities that depends on the weekend has no crypto equivalent, and any backtest that assumes one is modelling a market that does not exist.
Where the daily expiry changes the feel
Decay accelerates sharply in an option’s final hours, and because crypto has an expiry every day, there is always a contract in that terminal phase somewhere on the board.
For a buyer that is brutal — a same-day option can lose most of its extrinsic value within hours of being right about nothing in particular. For a seller it is the attraction, and the risk is the mirror image: the same conditions that make decay fast make an adverse move catastrophic relative to the premium collected.
Theta against vol, not in isolation
The decay you collect is only worth having if it exceeds what the movement costs you. Selling a high-theta option in a high-volatility regime is not free income; the theta is high because the option is priced for movement.
Which returns to the only question that matters for a premium seller: is implied above what will actually be realised — the comparison in implied versus realised volatility.