PurposeThis paper aims to identify psychological factors that influence people to be involved in Ponzi and pyramid schemes.Design/methodology/approachA psychological approach to finance or behavioural finance is applied in this research because of the assumption that human beings are not always rational. The sample consisted of 98 investors in 11 cities in Indonesia who were or had invested in an investment program with a Ponzi or pyramid scheme. The snowball sampling technique was applied.FindingsThe conclusion is that optimism (emotional bias), confirmation bias, representativeness bias, framing bias and overconfidence (cognitive bias) positively influenced investment decisions related to Ponzi and pyramid schemes.Originality/valueThe novelty aspect of this research is the implementation of a behavioural finance perspective to answer and express the fascinating phenomenon of Ponzi and pyramid investment schemes.