So what is your perspective starting a Career as sng player even if you only play for fun and some nice little extra cash?
Same as with any Career. If you are deep into it and really want to do it, results will come over time. Do the maximum research, have clear set goals for studying, grinding and results/hourly that you want and then compare to the people that play those games by reading their blogs, checking sharkscope and such sites, talking to regs who play those games etc.
"Nice little extra cash" can be 10$ per week or 1000$ per week. Difference is huge of course, because 1000$ extra per week requires you to play full time low to mid stakes with mass multi tabling; 10$ per week you can play stress free with less tables and less sites. Everything in between for extra cash is well everything in between!
Lets take i.e. HT 6 max or Turbo 6max STTs. Can you still play them profitably pre RB on Small to Midtakes having a real Job and maybe investing around 10-15hours/week?
You ask about small to midstakes and you talk about 10-15 hours per week investment? Please tell me you are joking about this?
If you want to beat today's mid stakes or higher low stakes, bar for such success has been raised a lot in past several years. Mostly thanks to Solvers and sites providing all the possible strategy edges + coaching and staking stables. So my answer is, no, don't think you will make money on mid stakes with 10-15 hours investment per week. You should have really strong knowledge of ICM, ranges pre and post flop , tendencies of limits you play, strong hand reading skills (range vs range, equity, textures, bet sizings) to be able to cruise and do recreational 1.5-2 hours per day grind on such stakes.
And if not, where could you play them and get the RB you need to show a profit?
This all depends on your skill and limit of course as well as multi tabling skills. If you are good enough to beat low stakes then you don't need to depend on RB heavily as someone who is BE or beats game slightly. Of course best site or network to play is one that offers best RB and highest traffic. So you need to do your own research for such things because that is exactly where regs find edge - finding most +EV deal and site where they can keep printing money. Nobody will hand you this information free especially if you are another reg coming to make games more difficult.
Or how far do you have to move down to make it work and is it then even worth the 10-15hrs you put in there?
Depends on your current level of knowledge, how tilt prone are you and how is your BR. I would start at micros for a month or two, get proven track record that I can still beat games pre RB well and then head to low stakes and see what happens. Low stakes players become better vs micros but they are still beatable because they lack post flop knowledge. Also, most opponents on any stake, suck playing HU because ranges are wider and tendencies pre and post flop shift drastically so if you are good or great or amazing at HU, you should have way less trouble having strong ROI on any stake.
So, to put it a little drastically, why should any poker enthuasiast start playing sngs in 2018? Just because it is fun? I mean, having fun and passion for the game is central to being succesfull but most people want some kind of perspective when choosing their main game...
This is why I asked you about hourly goal. If you don't know where you are currently with skill level or estimating your hourly and have no goal what hourly you want, I can't give you answer. I am however sure that if you are good solid reg and can beat low to midstakes, mixing sites and multi tabling you will get traffic in, get solid RB and still be able to make 20+ eur per hour. Now, if 20+ eur per hour is not good, switch game format, play spins or go to CG and be ready to go all the way up if you want to even get to 50+ eur hourly.
Regardless of which road you choose, games are harder then they were several years ago and you will need a lot of work to catch up and even more work to stay sharp and ahead of curve. I see guys quiting poker every day because its just "too much" pressure for them to handle work on and away from tables.
If you are looking for recreational approach, then don't set any monetary goals, just study and play whenever you feel like it. Your results over time should be positive regardless of stake. If I had 15-20 hours per week for poker, I would head to live poker room and make money there. Guys there that play nl200 , nl500 are at level of players online of nl25-50 at max, just gotta be able to take the swings mentally and have BR for it.