There's this thing called context.
PS1 - huge hit, easily won its generation and had a huge tail after its successor was out, made lots of money
PS2 - mega hit, dominated its generation and had a huge tail after its successor was out, made lots of money
PS3 - bomb at the start, crawled to its total over a cold-war prolonged generation through massive reinvestment and losses, came third in its generation, sales collapsed after successor was out, lost more money than any other console in history
PS4 - big hit, easily won its generation, made lots of money
That's not what I call consistency.
PS1 - Released in December '94 in Japan, successor launched in March '00 in Japan. Sold roughly 104 million units and was the highest selling console that generation (it's important to note the other competitors were far less successful in the home market). Part of the identity of the console was the disk drive, making CD's the primary platform to deliver games and gave the console extra media functionality. So five and a half years on the market before it was replaced.
PS2 - Released in March '00 in Japan, successor launched November '06. Sold roughly 158 million units and was the highest selling console that generation (it's important to note that competitors were far less successful in the home market). Part of the identity of the console was the DVD drive, making DVD's the primary platform to deliver games and gave the console extra media functionality. So six and a half years on the market before it was replaced.
PS3 - Released in November '06, successor launched November '13. Sold roughly 87 million and was the second highest selling console (it's important to note that this generation was the first in a long time to have not just two, but three competitors all sell a lot of units). Part of the identity of the console was the Blu-ray drive, making Blu-rays the primary platform to deliver games and a Blu-ray drive would become ubiquitous for modern devices at least in some part due to Sony's efforts. So seven years before it was replaced.
PS4 - Released in November '13, possible replacement in 2020 (maybe 2019). It released in the nascent stages of 4K media and neither HD console was prepared to make the leap to have a 4K drive, though by now PlayStation and Xbox cemented themselves as fully realized media consumption devices by this point. It has sold roughly 80 million, and will undoubtedly sell 100 million units by 2020 and will be the highest selling console of its generation (it's important to note that the competition was far less successful in the home console market). If the release window is accurate, it will be replaced between six years or seven years after release.
So, three out of the four generations it was the highest selling console of all time, with the PS3 being the second highest of its generation and selling almost 90 million units then. Three out of the four generations it played an integral role in standardizing the delivery method for physical media. The console life cycles lasted 5 1/2, 6 1/2, 7 and 6-7 years respectively.
So I would say that's pretty consistent. I suppose you can make the argument that the net loss for PS3 sales for most of the generation hurts the consistency of Sony, but are they not allowed a single outlier?
For comparison, every Nintendo home console sold worse than its predecessor from the SNES all the way to the GameCube to the point where if the Wii would have continued that trend its almost certain Nintendo would have abandoned the home market or been forced to do something drastic, but let's keep that in the alternate timeline. The the Wii was a huge smash. Then the Wii U was Nintendo's worst selling home console ever. And now the Switch is among the fastest selling consoles of all time and while we don't know what it's lifetime sales will look like because of the odd situation it finds itself in being the most powerful handheld on the market but a low powered hybrid console that will soon be up against two new consoles launching as the shine of the Switch being the new thing will have started to wear off. Mind you I'm NOT saying the Switch will fall off a cliff or even necessarily see a meaningful decline, just that we don't know what to expect. Nintendo hasn't had the financial disaster that the PS3 was for years (to my knowledge), but would I call them consistent? No. Certainly not recently.
And Microsoft isn't better. They launched a console that sold relatively poorly, then the second generation of Xbox sold extremely well overall (although the Red Ring of Death cost them, I believe, billions of dollars in revenue), and the third generation of Xbox has been...fine. It might end at 45-55 million consoles sold.
So with Sony, the track record says they will sell a lot of consoles next generation. Maybe 80 million. Maybe 120 million. Maybe they will be the highest selling of the generation. Maybe they will finish second or a close third in a generation with two or three very competitive consoles.
So respectfully, I disagree with your assessment and find Sony to be the most consistent overall.
