If arbitrage is your game and your goal is to sell bitcoin @ a high price on an exchange, then buy bitcoin on another exchange where its priced lower. There are regional differences which can be leveraged. A prime example of this are crypto exchanges in countries like africa which typically price bitcoin much higher than exchanges in other countries.
However it should be noted that regulation does not approve or arbitrage and has taken steps not only to shut down arbitrage opportunities but to make it more difficult for people to know the buy and sell price of bitcoin and crypto currencies in some places.
Random exchanges offering to buy or sell crypto at outrageously exaggerated prices should trigger suspicion. Big unexplainable swings in prices outside the realm of market mechanics can sometimes be scams.
x-crypto.com is a scam website to not use at any cost. The guys running this website are so desperate that they are paying people to spam on several forums. They are well known to spam the web. If they could, they would spam the bus stop by gluing advertising posters
This guy knows what he's talking about ^.