Sounds like your macro game is weak and you aren't pressing your advantage when you do gain a lead.
Some things I see fed top laners do that carry games in lower elo:
Use TP for lane backing only the first time. After that it's to make plays on the map and capitalize on their lead (general rule of thumb).
Shove lane/kill laner then immediately roam. Either opponent jungle or mid (or in the case they are very far ahead, both). If you can't tower dive, you can usually take the enemy jungle camps, and possibly the jungler.
Take Heralds obviously.
Keep an eye on scuttle early, if its spawning you can probably feed your mid/jgl by walking over there.
If you saved TP as you should've, securing drakes.
If you're already 6/0 or something and TP say bot, give your ADC/mid the kills. A lot of people in gold get fed then just take every single kill. That's not the optimal way to carry imo.
Rolling off that last point, don't take every single kill just because you can. You're all in the same elo, odds are very high that if you get another lane as fed as you they can help carry too. A lot of people in low elo just assume everyone on their team is trash and they're the only key to victory. Most of those people are hard stuck with no idea why (JK, obviously their team mates right?)
If you're playing Morde (going off your history) don't just ult who you think you can kill. Take the fed person out of the fight. If you listened to my prior point, you'll win the team fight.
Learn when to split and when not to split and where to split. If Drake is up and your team is mid, and you're splitting top - you might be fucking up.
In Silver/Gold there comes a point where they game generally devolves into two scenarios: Either A) it's now an ARAM or B) Everyone is running around trying to pick or getting picked because they overextended somewhere. Take advantage of that.
If you're 20/2 and overextending forcing fights and you get picked at Barron or elder or something of significance, allowing the other team to take it while you respawn, then inevitably lose an inhib or worse - you threw the game harder than your entire team. Nobody gives a fuck about your KDA or end game damage. If you got a massive lead then dumpstered it by being stupid, that entire loss is on you. Don't be dumb with your lead, most come backs in low elo are because of this right here. Someone got fed then threw the game they could've won. Then inevitably they say some shit like "can't carry this" in all chat. Well no shit you can't carry this, you fucked up.
This should go without saying, but people obviously tilt easily in low elo. Don't spam ping or talk shit to your team, it does nothing useful. The only time you should be pinging is if it's of use. I've met some great players in gold, but they're very inconsistent and tilt off the face of the earth. This gets exasperated by every idiot who wants to ignore their own bad plays and ping everyone else's. Nobody in Gold is good enough to ping anyone, you're all doing dumb shit repeatedly.
Regarding lane control, don't push to their tower without wards and give up a shutdown. Your 1000 gold death to a Yi in Gold league can end the game. Doesn't matter if you're 7/1 at the end of the game, if you gave that guy the tools to snowball on other lanes - that's your fault. After a lead, if you can freeze the lane try to. Don't just endlessly shove to tower if you can't make use of it.
Overall, capitalize on your lead. Killing the Garen who is now worth a cannon minion does nothing for you after a point. Make plays on the map, be at objectives, and push for the win not for the kills. Use pings and chat to direct your team when necessary. If they aren't doing what needs to be done, play around them. Don't just go where you should be and bitch when they aren't there as you die. Use your team to your advantage.
Regarding losing lane, don't feed obviously. You don't NEED to stay even in CS when behind if it causes a death. Do try to get the experience though. A level disadvantage is massive compared to missing that cannon minion. If you have another lane that is winning, or getting ahead, there is no need for you to try and get ahead as well. Just go even or slightly worse and you win. That's it. Sometimes you just need to let someone else carry.
Not all games are winnable, but 60% or higher is perfectly obtainable by making the right decisions and capitalizing on what you can. The more you play and focus on yourself, the easier the climb becomes. Leagues are nothing more than a gauge of how rounded out a player generally is, if you're stuck in one its because you're lacking somewhere others aren't. Despite popular belief on the forum and in game, you don't need to be a literal God with all the luck in the world to climb. You just need to do decent and make some good decisions when it matters.
Also, because it is worth noting, sometimes you just fuckin lose. Sometimes everyone gets dumpstered. Shit happens, do what you can, but if its 2-20 at 15, just go next.
, but I have played against a fair number of them. The two things that set the ones that are good at him apart from those that are not are:
