Is it wrong to tout tickets?

I bought some tickets just to sell on to make profit. Is that wrong?

It feels immoral but obviously isn't illegal. Is it any different from any other business where someone buys a product then sells it on for profit?

I don't agree with websites like get me in or viagogo which buy up tickets in bulk and try and sell them at hugely inflated prices. I intend to buy only up to four tickets for events and sell them on for profit but not at twice the price - what do you think? Is it wrong or should I take advantage of the fact that I can buy them?