Despite the fact that Nicaragua has the lowest crime rate in Central America, lower than the US or Europe, as a 'wealthy' foreigner you will at least be considered a potential target by scam artists and thieves. Make sure they pick a different tourist by staying alert and taking precautions against theft and mugging. Several areas merit their own warnings, including Managua, with big-city problems; San Juan del Sur, with bohemian tourist-industry problems; and most of the Caribbean Coast, with serious cocaine-trafficking problems that you should steer well clear of.
Always play it extra safe in rural areas along the Caribbean Coast, undeveloped nature reserves and anywhere that infrastructure is limited and communications weak. Even if it's expensive or seems silly, consider taking precautions recommended by a reliable source - hey, if they think two guides is better, maybe there's a reason.