It's not because it's hard, it's because you didn't try.
Tips
grammar
是因为 is used in the pattern [result] + 是因为 + [reason], emphasizing the cause. Often paired with 之所以: 之所以...是因为... (the reason...is because...).
mistakes
Don't confuse the word order: in Chinese the result comes first, then 是因为 + reason. In English it's the opposite: 'because X, Y' vs. Chinese 'Y 是因为 X'.