That’s because “we” are a self-selected sub-group of private pilots. The majority of PPLs get out of flight school and are more or less terrified of flying, even just with themselves, let alone taking someone along and taking responsibility for their lives. It takes many some time and routine to get where the flying only takes half of their processing power, to allow for some of it being taken up by passengers. Some never get to this point. I guess it’s these who tend quit after two or four years.
It’s not my experience at all
It’s not really my experience either.
The majority of PPLs get out of flight school and are more or less terrified of flying, even just with themselves, let alone taking someone along and taking responsibility for their lives. It takes many some time and routine to get where the flying only takes half of their processing power, to allow for some of it being taken up by passengers. Some never get to this point. I guess it’s these who tend quit after two or four years.
Actually (the stats vary, and aren’t published or even discussed much because they are such an embarrassment for the national CAA and the European training system which feeds money to the CAA) most PPLs chuck it all in within a year or two, permanently. The UK (which is one of Europe’s Big Three GA countries) sees about 90% give up within 2 years, and informally I hear similar, perhaps slightly better, from the others.
But one can’t base advice to a potential new pilot on that – because the huge dropout rate is due to factors (again much discussed here) which are little to do with aviation e.g. most are doing a PPL to tick off an item on a bucket list / to spend 10k they got for xmas / etc / and were never going to fly in the long term. We don’t know if the OP is in that category, and probably he isn’t since he is doing the right due diligence right at the start (which most don’t).
The bottom line is that flying alone is actually pretty damn good 
Male passengers are hard to find because most men have to work all the time otherwise they end up in the gutter, and female passengers are, ahem, “tricky” unless you are both single and fancy each other Consequently, passengers are really hard to find – even for day trips.
In my mind, the best thing about flying is taking up non-pilot passengers who really want to go flying.
Many years ago I failed to get the medical I wanted. I went away from flying for a number of years, but eventually came back to it and do a different kind of flying, but one that I still get a great deal of enjoyment from. I do regret walking away from it, but even with hindsight it was the sensible decision and I have little or nothing to complain about as a consequence.
Only you can answer the question of whether you want to continue training with this limitation, but I would say there is much pleasure and satisfaction to be found in every type of flying, and some of my most satisfying flights have been done solo.
Mitor wrote:
Or is it more common to fly solo
Definitely more common to fly solo. After that it’s flying with another pilot. Flying with passengers is rare IMO. I can count on the fingers of one hand the times my wife has come along. The trip that sticks to her head was a flight in a AA-5. Then I flew with another pilot and she sat in the back. The AA-5 is rather nice and maneuverable compared with a Cessna/Piper. Long story short, we forgot all about her sitting there in the back, 100% focused on testing how maneuverable the plane was
One of my sons like to come along. He now has his own license. The other two has shown no interest. They have come along a couple of times.
We seem to have very different views and experiences on this. When I got my license I immediately started flying with non-pilot family and friends, usually filling up all seats. I found it very rewarding to offer such a thing to such invariably happy ‘customers’. I do not recall having taken up someone who did not like it or was indifferent to it. I was in my early thirties with a family and could not yet afford flying a lot without asking for a contribution to the cost from the passengers, but the main driver was still sharing this wonderful experience. Other than flying with pax, I flew with fellow flyers to do longer cross countries, prob about 25% of the time. Sharing the cost and the fun. I actually think I never flew solo the first 10 years or so. This was in a club environment. But continued to do this after becoming an owner. Well, minus the cost sharing.
And, as an aside, a very rewarding experience was that I cured some people from fear of flying. I was surprised about that. My theory is, right or wrong, that for those persons ‘seeing what happens up-front’ and ‘the assurance that one can be back on the ground in minutes if needed’ is a great help to overcome their fear.
I now do a mix of flying solo and with someone else, mostly a non-pilot. And still have a waiting list. The fact that I fly a bit more solo now is that not everyone is open to get out of bed before sunrise to fly in wonderful light, especially not in their weekend 
Like most pilots, I am not fortunate to have a spouse, nor kids, who share the passion. They are not afraid, but just see it as a means of transport. I will not easily forget a flight to Malaga, inbound over the magnificent Sierra Nevada when I looked at my daughters in the back seats vast asleep..
