I just recently reached 500 000 known words in LingQ in all languages combined.
Take into account though that 1) Known words in LingQ are word forms, including different conjugations, declensions, compound words etc. 2) I mark true nouns as known, which is debatable 3) Some of these numbers are from reading languages I was already fluent in or even a native speaker.
The languages I was fluent in before starting to use LingQ are Icelandic, English, German, Swedish and Danish. The languages I learned in LingQ that I was not fluent in already were French, Dutch, Norwegian, Spanish, Italian and Polish. So far I got to advanced 2 in all of them except Polish, where I am at advanced 1.
I have used LingQ as a springboard to be able to speak fluent Norwegian and somewhere between conversational and sub-fluent French, Dutch and Spanish. I can not speak Italian because I will almost always think of Spanish or French words when trying to, but I can read it pretty easily. My Polish is very limited. I can hardly string together a sentence except maybe to ask to buy simple things. I can read simple texts fairly easily and I get some limited sense out of news I read.
My takeaways are mainly these: 1) I think becoming literate through reading with the automatic translations offered here and then following that up with listening, if you really put in the hours, is an excellent springboard into starting to converse and eventually becoming fluent in languages. 2) Because of the gamification of trying to achieve high numbers of known words, it’s easy to fall in to the trap of overemphasizing reading, at the cost of listening, writing and speaking. 3) It’s also easy to fall into the trap of trying to read too much material with new words instead of trying to repeat lessons to consolidate your understanding. Lots of words you can gain are international words that are the same or similar across languages and while they will make your word count go up, you won’t really be learning much by marking them as known. 4) I think reading material first with translations to increase your passive vocabulary and then listening to the same material to be able to catch the words in their spoken form is an excellent way to get a good passive vocabulary. 5) You absolutely still have to eventually take that step where you start working on output and interactions, really using the language, corresponding with people and especially conversing.
All in all. I have gained a lot from using LingQ, even though I have at times fallen into the trap of chasing the known words count too much. I have also at some points burned myself out. I think it’s important to know when to switch when that happens, maybe take a break from LingQ and watch some videos instead or just take short breaks from language learning in general.
I hope this helps you who are learning languages here on LingQ and elsewhere.