[brookside]

Can I ask why do living costs increase with years? I believe the general trend is people having less expenses after they retire.

The calculation in the link takes into account inflation, so that (massive) aspect of increased expenses is included in the prediction.

Edit - If indeed you are planning to increase your living expenses after retiring (bigger living quarters, more expensive travel, etc) that would certainly lengthen the amount of time of work needed to achieve financial independence.