[stonecold_1981]

Spirit is tagged the most hated airline for a number of very valid reasons. But, your complaint just does not have any merit.
For an airline that has regularly advertised itself as providing the "cheapest" airfares (with everything on top of basic transportation at extra cost), it is relatively very easy to figure out how much a "total trip cost" would be. In just two clicks, you can reach the baggage information page which outlines the additional fees.

Further, your argument "How do you expect anyone to carry everything in this limit for 5 days" is irrelevant. Do you really think that this airline plans the baggage limitations based on how many days you intend to travel? Their value prop is straight forward, and I would have thought well understood - provide the cheapest airfare and charge for everything else. That allows passengers to pay only for what they use.

While broadly regulation is surely required in this industry, and particularly for some of Spirit's practices around customer service, it would do not good if people fail to take responsibility to assess the true cost of a flight.