caprice; whim; passing fancy
Before you marry, ask yourself seriously if this is a love that is likely to endure for life, or just a passing vagary.
vagus (roving, wandering) (Latin)
A vague person shows vagary Sounds like beggary. If you invest too much money in the stock market, it may lead to beggary because of the vagary (unpredictable) nature of the stock market.