The basic premise of economics is that you buy things that cost less than they are worth to you. That is the foundational principle of economic exchange. It must be more appealing to me to exchange what I have for what I want than keeping what I have. Worth and Cost are in competition with each other, they are very much not the same. Value is generally seen as the difference between worth and cost: if something is worth $10,000 for me, and I paid $5000, then I have had a transactional value of +$5,000. If something is worth $2,000 to me, but I paid $5,000, then I have had a negative value of $3000 on the exchange (which, generally speaking, rational people will not do, but desperate people sometimes will).
They are not the same.
Worth can remain constant, while cost goes down, increasing value. Cost can even go down, while worth goes up, increasing value. Cost can go up while worth remains constant, decreasing value. Worth can go down while cost remains static, decreasing value.
They are not only not identical, their movements in economic scale aren't even inherently correlated (well, value is to the relationship between the two, but cost and worth are very much independent of each other).