A megaphone is a naive and unsuitable analogy.
Money buys you the two-party system where the only viable candidates are the ones that have been paid for, that do the bidding of the lobbyists and special interests that actually dictate national policies and run the country.
Money buys you the mass media, that surrounds and saturates the public with messages, dis/misinformation and values skewed to suit your agenda.
Money buys you the power to shape laws and regulations, so that your industry is.. You get the idea.
"Money governs access to political power in this country."
As an American, I'm ashamed to learned over the decades how much this statement is true. Didn't you see how money bought the presidency? How else did we end up with utterly corrupt and incompetent (or maliciously competent) politicians running the country?