First, who is #2 is highly subjective, if you discount nuclear arsenals.
Second, this question is like asking Compared to a Ferrari a Mustang outruns tons of Priuses, Civics and SUVs. And it costs a lot less.
Does that mean a Mustang is anywhere close to a Ferrari in speed?
The US is, by virtue of its spending, #1, no question. It deliberately has put itself in a similar position as the Royal Navy's old bigger-than-the-next-two-navies-combined doctrine.
It could spend a lot less, it would still be #1. Maybe with a lot smaller margin, but it could trim its spending. A better question might be: why does the US electorate put up with this level of spending, with the USSR gone?
This doctrine remained in place until 1989–90, when President George H.W. Bush ordered the "Base Force" study which forecast a substantial cut in the military budget, an end to the Soviet Union's global threat, and the possible beginning of new regional threats. In 1993, President Bill Clinton ordered a "Bottom-Up Review," based on which a strategy called "win-hold-win" was declared—enough forces to win one war while holding off the enemy in another conflict, then moving on to win it after the first war is over. The final draft was changed to read that the United States must be able to win two "major regional conflicts" simultaneously.
So, the US is #1. Who is #2?
If you count in nukes, yes, that's Russia.
Without them? Not so sure. Their actual operations aren't always amazing. For example, their aircraft carrier had to be towed around in the recent Syria engagement and and caught fire later. Yes, they decisively beat Georgia in 08, but... Georgia? And even then, not everything was rosy - there was significant criticism, external and internal of their performance, which may have been corrected. In Chechnya, they massively goofed up in the first Grozny battle because of untrained troops and horrible tactics.
They, to answer your question, get a lot of theoretical bang for the bucks by using cheap conscripts. Would they be up to snuff in real combat - (check that Grozny link)? After while, sure. At the start?
In terms of budget, a lot of their equipment is, like the US's B52s, Cold War era, so needs no procurement. And they may have better control over costs than the Americans with their F35s, though they also wasted untold amounts of money through corruption in the 2014 games.
Some of their new gear really does look pretty good however, but they may not always be able to buy enough for that to matter.
Fighting in Europe, they would trounce the European forces (minus the US). For a while. But then they just lack the industrial infrastructure to keep it up if they don't win right away. They might still win, but more to European military weakness than due to their own merits.
And now you have China. Do you want to bet they could beat China in conventional war? I wouldn't, but that's exactly what your article claims. Not that they aren't nice to China, giving it one aircraft carrier, and not picking up on the fact that it's largely a training carrier, to get Chinese naval airpower doctrine figured out - the real PLA carriers are yet to come.
Does that mean China can beat them? Not sure, now. As time goes on, yes, China will be gaining.
Weakness in article
Wars are, to a degree often underestimated by people, determined by the training, morale and quality of the weapons, not just sheer numbers, which seems to be all the linked article cares about. Look the UK's #8 position, well behind Japan (which, I was intrigued to hear, has 4 aircraft carriers). Yup, makes a lot sense.
Look at Israel, not just now, but 40-50 years ago. The numbers looked one way, the actual wars went entirely another way. In 2003, the Iraqi army was 4th in the world. I bet that NK is very impressive, in sheer numbers.
- Russia may or may not be #2
- US spends so much that whoever is #2 is nowhere close to it so this question isn't as meaningful as it might seem.
- This Business Insider article reminds me strongly of those Top 10 This-or-That videos on YouTube.
edit: globalfirepower.com, the primary "source"
With its numerous consumer ads, pompous domain name, Lego-styled design and PwrIndx (™) , these guys look they publish cat videos for armchair generals. Saudi Arabia #17, Israel #18. The Houthis must be quaking in their boots.
US: 0.0606, Russia: 0.0681, China: 0.0691. What, next, Death Star: 0.001?
What, and this relates directly to the title of the question, does the difference between 0.0606 and 0.0681 even try to convey, besides implying a near-match?