Yeah, let’s assume the music is good. It often isn’t good though, and a lot of good and/or expensive self-promotion goes into very bad or painfully mediocre music. I won’t go too much into that, because while well-promoted bad music is all over the internet and people’s ears, it hardly ever lasts.
In the age of the Internet and social media, I think the idea that “if the music is good, people will listen to it” is especially counter-productive. Coupled with the fact that there’s so much music around right now that people forget in August the artist who made their favourite tune of July, I think just making good music isn’t good enough. Sending it to a few friends and hoping for the best won’t cut it: people won’t hear your music, and if they do, they probably won’t care.
Some solutions are, as you said, paying for likes or reposts or to spam the hell out of everything. This is usually counter-productive, especially if the tune in question is the first bit of music people hear from you. People, and DJs in particular will associate you with being a spam guy, and may start ignoring you. Keep in mind that most music isn’t good. Couple that with being an unknown spamming people who check out music for a living and you’ll realise that your tune being on par with the best stuff out there won’t save it from being chucked out with the rest of the spammy promos.
I think the key to getting your music heard is longevity. I’ve been seeing a lot of ebooks, forum posts, YouTube videos, etc, talk about doing hardcore promo for even the first tune you feel is good enough to ‘release’ (which, to my initial surprise, now means uploading it to SoundCloud as a free download with some artwork - which is fine by the way). I don’t think this works necessarily. You could blow up if you’re that month’s luckiest bedroom EDM producer in the world, sure, but not in dubstep or any other niche bass music genre. What I’m saying, I guess, is that if you feel your music is good enough to be out in the world, you should patiently work on building a following, and slowly grow both as an artist and a ‘marketeer’/someone who wants to build a career out of this.
This is not done by buying reposts, shares, or anything. I don’t even think hitting up blogs is at the core of it either (it is very useful if you’re releasing an EP or an album, obviously, and the role of blogs is probably different in more mainstream forms of electronic music). You should hit up a couple of DJs with your best 2 or 3 tunes, upload some bits to SoundCloud, give away a free download or two at some point, talk to people at nights, do promo mixes, etc, to get a couple of people to start listening to your stuff and support you.
Obviously that’s not enough. Next you could try and get some DJ bookings, maybe collab with some producers whose music you’re into, or release an EP on Bandcamp.
Finally, and most importantly, in the social media age, to cut through the noise, you should focus on engagement. Get some followers on social media. Real ones, not paid bots. Also don’t follow and unfollow people on Twitter. Don’t tag 90 people in your Facebook posts. Just ride it out, make good stuff, and provide your listeners with a steady(ish) stream of ‘content’ (yikes). Using Facebook, Twitter, Snapchat, Instagram, or whatever, ask people questions about music or other stuff that’s important to you and your listeners, post a relevant meme from time to time, share videos of what you do in the studio (btw, the studio is usually the bedroom, that’s absolutely fine), post music or art you like so people can see what you’re about. Retweet a friend’s awesome album. That kind of thing.
People will see you, some people will remember you, and there will probably be some people who will support you and your music. Don’t watch the numbers on social media too much. As long as they’re going up and not down it’s good. It’s better to have 50 long-term fans than 10.000 plays on one track. The fans will be there next week; those 10.000 plays probably won’t be worth much by that time.
TL;DR If you focus on promo on a tune-by-tune basis, you will probably be forgotten right after most people’s first play. Focus on engaging with people who are actually prone to liking what you make, and things might work out.