The answer present a rare and one-dimensional perspective. The obvious reasons could be:
If you have worked on the above, then consider Askssl solution
Do you have an SSL Certificate? If no, the customer might have spotted the ‘insecure’ browser warning and taken heed.
Are you using a Free SSL certificate from Lets Encrypt, Cpanel, Cloudflare, e.t.c – the customer may have checked and confirmed you do not care much about his or her data security and fled.
Solution: Invest in a commercial SSL certificate – We recommend OV or EV SSL for ecommerce businesses.