credit card is an bad idea cause it´s unsafe as @journeyoflife mentioned.
As Steem is decentralized there is no company that provides Steem for all to buy. You will need an exchange where you can buy from any people who want to sell. But this is not the Problem we already have this somehow (blocktrades). Problem is the gate to Fiat where different laws in different countries take place. I think in Germany for example you need a Banklicense. (No Bitcoin ATM in Germany for example) ... and so forth and so forth , I´m not a lawyer