My this is some thread. I won't touch on the generalized opinions of the OP, but rather a few thoughts after reading the whole thing.
-Yes it was harder early on than now, by a lot. I started in early 2015 and just started an alt recently. Someone posted a mention of Sept. 2015, and yes that's around when the first real cashcows began. Prior to that, with a few temporary exceptions 15mil/hr even in an Anaconda, the largest ship at the time, was essentially impossible. Now that's easily doable by a number of means - whether or not any given player is aware of all/any of them. I can't think of an activity - the intended activities that is, not the one-off cashcows - that pays less than in 1.2, and most max out a whole lot higher.
-If the goal is making money, then some flexibility must be allowed for. Someone's comment "making 1.4mil/run trading in my Python..." fella, it's because you're trading, and that has well known limits especially based on scale. If you're fixed on one activity then you're fixed on that activity's limitations.
-While obviously some people are just abrasive, and many got their millions/billions within days of starting, I wouldn't paint every 'moneybags' player with the same brush. Some of us just learned over time where the money is in the 'regular' game, outside the recurring unintended/exploity bits. It helps if you're in some community, Discord or otherwise, as you'll find out through the grapevine and be able to discuss the wheres and hows in a more fluid and immediate way than sifting through the forum. Most things you might want to learn in detail in this game you'll only learn from other players.
A few examples then, toward your goal:
-Missions are rep-based availability. That means if you stay in one place and take the time - yes I know that part can be tedious - to build your rep with multiple factions (faction, not superpower, rep lasts forever if you don't do anything to harm it), you'll find yourself offered an awful lot of individual missions with rewards well into the millions of credits. Even in something like an Asp, not even stacking to the gills, you can turn that into perhaps 15mil/hour just about anywhere, though it's quite variable. I have several systems where I'm allied with everyone from trading early on, and at no point since 2.1 have those systems failed to offer me multiple missions for millions of credits. Even in 2.3, with lower rewards than now, my brand-new alt in a Hauler was getting 1mil credit passenger delivery (i.e. named but one-way VIP) missions - a few of those in you're in an AspX (or a cheaper T6, if you choose). A few more and you're in an a-spec AspX, which opens the door, provided you've built the rep, to the 15mil/hr gameplay mentioned above, and seemingly passenger fitted quite a lot more post-2.4 (and yes, still a great deal more than 2.3 after the nerf of 2.4.02).
-Exploration can be done just fine in a Hauler (this isn't about your choice of ship), better ships just make it faster and/or allow you to carry more stuff. Advanced DS and Detailed SS are all you need for credits. Following one of the Earth-like lists you can find, in the course of say, a week of your playtime, you can scan enough Earth-likes to get something over 100 million. Using those credits to get something better (e.g. the aforementioned AspX), you can do it faster, and in a short period be in one of the Big 3, namely the Anaconda.
-The Cutter (or Vette) specifically...no workaround there. It's a tremendous grind meant as a gate for everyone. I think many games have such things for which there's no shortcut to unlock and these are just Elite's. It'll likely be changed once the current explicit-placeholder state of superpower ranking is fleshed out, but for now time is the only currency you can pay to get these.
Edit: Oh, combining efforts would be a good idea. Building rep somewhere and using that for your credit goals? If going for a Cutter, do it in an Empire system with multiple Empire factions, and every mission you do for them will keep pushing your rank up. 2 birds, one stone, you get it. I'd recommend somewhere with multiple starports and a bunch of Empire-aligned factions, say Cemiess off the top of my head. Very high-population which can't hurt. Each starport has it's own board, if the one isn't giving you anything worthwhile.
Before this gets too long:
I know plenty of heavy RP guys who stick to their characters' career (trading, mining, scavenging, whatever) strictly and that's fine, but the income-limitations of that career must be considered. If your goal is to progress credit-wise, look outside your activity "box" and you'll likely find a better avenue. You can always go back to your path once you're at the level you wish to be.
Far too many assume an avenue to riches doesn't exist when it's only that they haven't learned enough yet.