Is being a sniper harder?

Yes, and it is for two reasons, these two reasons are billeting and

Standards and requirements. The term sniper covers a broad range of soldiers with varying skillsets and roles. Billeting involves the number of soldiers that are trained to be snipers.

Not everyone in the military can become snipers, as they usually don’t require a lot of snipers. Secondly, standards and requirements are different in each country, and each country has its own operational requirements and so forth.