Myth: Some accents are harder to learn than others.
Truth: The perception that an accent is ‘easy’ or ‘hard’ to learn is entirely relative. What is hard for you may be a piece of cake for the guy sitting next to you.
Accents that seem easy to learn typically have many sounds in common with your own personal dialect. Or, within your personal life experience, you may have had significant contact with some other dialect that has sounds and features in common with the one you are endeavoring to learn. For instance, if you grew up in Nebraska and so did both of your parents, but from the time you were two years old until you were nine, you had a live-in guest from Paris, France who spoke English with a French accent, you may find it easy to learn most of the phonemes that happen to be part of that French accent simply because you were exposed to them for so long and at such a young age. You might then in turn find it ‘easy’ to learn some type of Belgian accent, which happens to contain certain phonemes that are also common to Parisian dialects.
It’s not that the dialect itself is easier. It’s that you had a head start.